The military history of Ukraine begins with the Rus, an umbrella term for the predecessors of the modern Ukrainian, Belorussian, and Russian nations. During the Middle Ages, two major Rus states sprung up between the Carpathian Mountains and the Dnipro river: The Principality of Kiev (often referred to as the "Kievan Rus") and the Kingdom of Ruthenia (also known as the Principality of Galicia-Volhynia). These two states rapidly became major powers in the region, renowned for the military prowess, and the Byzantine Empire often recruited Kievan warriors to fill out their armies. The Mongol invasions, the rise of Poland and Hungary as major powers, and political turmoil led to the decline of these proto-Ukrainian states by the end of the 13th century.
Fleeing violence, many serfs in the area migrated to the sparsely inhabited and loosely controlled "Wild Fields", in what is today southern and eastern Ukraine. This gave rise to the Zaporozhian Cossacks. Living in democratic and self-governing communities, they were nonetheless autonomous vassals of the Polish-Lithuanian Commonwealth. The latter integrated them into their army as "Registered Cossacks" formations, as the Poles and Lithuanians needed them to guard their borders from the Turks. The Cossacks became known for their tenacity as soldiers, particularly serving as powerful cavalry units (the mostly flat terrain of Ukraine making horses especially useful).
Then, one Registered Cossacks commander, Bohdan Khmelnytsky, led a successful uprising against the Poles, creating an independent Ukrainian Cossack state known as the "Zaporozhian Host", which then becoming an autonomous vassal of the Tsardom of Muscovy under the Treaty of Pereyaslav. The Cossacks of Ukraine served much the same role in Russia as they had in Poland-Lithuania, maintaining political autonomy in return for military service. This lasted until the the Zaporozhian Host was liquidated under the order of Catherine the Great, absorbing their forces into the Russian Imperial Army and placing the people of the area under direct Russian rule.
In both World Wars & the Russian Civil War, there were Ukrainian armed groups who found opportunity to escape prolonged Russian rule, as well as those who served in the armies of Russia. In World War I there was the Austrian-formed Ukrainian Sich Riflemen, which recruited local Ukrainians for revenge against the Russian Empire, who then formed the backbone of the short-lived Ukrainian People's Republic in the Russian Civil War before being crushed by the Soviet Russian Red Army. There was also Nestor Makhno's Ukrainian anarchist forces, with their Tachanka, (horse-drawn carts with machine guns). They initially fought alongside the Red Army, but were later betrayed and destroyed after the Bolsheviks defeated the White Army and had no more use for the alliance with Makhno.
Later, in World War II, the Ukrainian Insurgent Army was formed to liberate Ukraine from Soviet rule. They initially collaborated with the Nazis, but later battled them as well after it became clear that the Nazis had no intention of establishing an independent Ukrainian state. They also frequently clashed with the Polish resistance (who were seen as territorial rivals). The nature of their relationship with the Nazis, as well as their atrocities against Polish civilians, remains controversial. Nonetheless, they fought against the Soviets until the early fifties, with intensity comparable to the Soviet-Afghan War.
Rusty Tanks and Rusty Soldiers
Following the breakup of the Soviet Union, the newly-independent republic of Ukraine took control of most former Soviet military assets on its territory. The major exceptions were nuclear weapons (which were given up to Russia on the understanding that the latter would respect Ukraine's sovereignty), the majority of the Black Sea Fleet, and the naval base at Sevastopol.
Under the auspices of the Treaty of Conventional Armed Forces in Europe, Ukraine was entitled to an upper limit of 450 000 men under arms; in practice, this turned out to be too much for the young nation, thus cost-cutting measures. In fact, the ZSU (not the Soviet SPAAG, but the Zbroyni Sily Ukrainy, literally Armed Forces of Ukraine) were systematically cut in size, funding and materiel literally every single year since at least 1998 - first as a cost-saving measure, then under the auspices of reforming to NATO standards, then... something else. By 2013, the Armed Forces shrunk down to 150 000 men strength. On paper. Then Crimea happened.
In 2014, the decades of neglect resulted in a rude awakening, as the Ukrainian military was utterly unprepared when Russia launched an invasion of the Crimean Peninsula. At the time, it was estimated that only around 3,000 troops of Ukraine's "on paper" military were actually combat ready. This resulted in Ukraine being forced to withdraw from Crimea. Russia then pushed onward with its efforts to destabilize the country, funding and arming extreme Russian nationalists in the Donbass region to launch an armed rebellion.
War in the East
However, the Ukrainian army may now turning into a Badass Army candidate with this "War in Donbass", holding their own against both well-equipped Russian-backed insurgents... and "Russian-backed insurgents" that are actually just Russian military troops with their insignia removed. Bonus points for doing it while being chronically under-equipped.
The Armed Forces are divided into the Army, Navy and Air Force, with the Navy being notorious for having more admirals than ships and the Air Force being likewise notorious for not being in the air that much; the average Ukrainian fighter pilot had only about 10-20 flying hours prior to 2014, and the fighters themselves were often short on fuel. It currently experiences a shortage of planes due to a number (mostly Su-25 Frogfoots) getting shot down in Donbass by Russian anti-aircraft weapons.
The Army, on the other hand, is the service branch most heavily engaged in the fighting proper, as well as possessing the most firepower (more on that firepower below). Among its relative successes is the near-legendary siege of the Donetsk Airport (which lasted for 242 days before both airport terminals collapsed, leaving it indefensible and forcing the garrison to pull out); for their incredible resilience and spirit, the airport's defenders are widely referred to as 'Cyborgs' by Ukrainian media, public and government both.
Army units, especially the Airmobile Forces (airborne component that ends up not being very airborne), Armored Forces and the artillery, generally have done most of the heavy lifting in the war; the Navy occasionally chips in with the Marine Corps, a brigade-sized detachment of Ukrainian naval infantrymen, and the Air Force, which used to harass the separatist forces from the air. This contributed to the insurgents "acquiring" Russian-made SAM systems and the ill-fated shootdown of the Malaysian Airlines Flight MH 17 in mid-July. The other participants in the war are the National Guard and the volunteer batallions, elaborated on below. In addition to the war in Donbass, the Army is also busy with securing Ukraine's (rather shoddy) borders with Russia, occupied Crimea and Transnistria.
Despite the country sitting on a treasure trove of Soviet military hardware, most of that hardware turned out to be rusty and generally out of working order in the next 23 years, with the most functional examples being sold abroad. The Ukrainian defense industry therefore struggles with getting that hardware into working order and trying to get the defense industry itself to produce all the cool stuff designed during independence. The T-84 Oplot, for example, may be a Cool Tank, but most of them being produced now are intended for Thailand, while the Army has to do with 30-something T-64s (also a one-time Cool Tank) and their modifications. Ukraine also has the only shipyard in the former Soviet Union capable of building aircraft carriers, but didn't (and probably won't) do anything particularly productive with it; an indigenous Ukrainian corvette, the Volodymyr Velikyi, is stuck at about 75% complete, and until 2014 newest ship in the Navy was commissioned in 1998. Similarly, Ukraine inherited the world-famous Antonov Design Bureau and its An-225 Mriya record-setting cargo aircraft, but most of Antonov's newest planes were intended for Russia, and another Mriya simply can't be built.
A modern SRBM project by Yuzhnoe Design Bureau (they of the SS-36 Satan fame) was quietly buried during the pro-Russian Yanukovych presidency. It was revived after the war began, though progress is uncertain. Licensed production of the Israeli TAR-21 and Galil ACE was negotiated all the way back in 2008, but it barely started last year, and both rifles are in the middle of their state acceptance trials (Ukrainian troops instead have to do with trusty old AK-74s, fitted with rails and red dot sights). While the defense industry is busy getting into high gear, it is mostly stuck with refitting older hardware, and the future of some of its industries is uncertain to say the least.
Auxiliaries and Volunteers
Along with the Armed Forces (under the Ministry of Defence aka MO), Ukraine also has the National Guard gendarmerie/military force of the Ministry of Internal Affairs (aka MVS, short for Ministerstvo Vnutrishnykh Sprav). For added confusion, there was a National Guard from 1992 until 2000, when it was reorganized into Internal Troops (conscripted riot police as in Russia). Said Internal Troops then got re-branded back into National Guard in March 2014, together with an influx of new blood, such as resistance fighters from the Euromaidan movement. With the war going on, the National Guard also had to learn the ropes on the fly, but has acquired a reputation for getting new stuff (or, well, any stuff) way ahead of the military proper, starting with BTR-4 APCs (originally intended for Iraq) and lately with new MRAPs, APCs, artillery, assault rifles (a Ukrainian licensed copy of the Israeli TAR-21) and new Cadian Shock Troops-esque uniforms. The latter could be intentional, since the current Minister of Internal Affairs is a science fiction fan.
The MVS also often sends police officers into the area of confilct, primarily traffic policemen (known in Ukraine as DAI, or Derzhavtoinspektsiya, literally State Traffic Inspection) and riot police troopers from the infamous disbanded Berkut unit. These primarily man checkpoints in the wider Donbass area, and not the frontlines proper. Donetsk Oblast police have recently also demonstrated professionalism above and beyond the call of duty in towns close to the front line, especially in the beleaguered town of Debaltsevo.
As of April 2014, the Border Guard and the State Emergency Service were also absorbed into the MVS structure. The Border Guard now has its hands full maintaining the Ukrainian border, especially with Russia and Transnistria, and its maritime component, the Sea Guard, ended up having more ships than the Navy proper, after Crimea happened.
Ukraine also has a number of special forces units, either under the GUR (military intelligence), the SBU (internal security service), or the UDO (people in charge of the President's security). All of them had seen action in the war, particularly its opening phases. Army special forces, particularly the Kirovohrad 3rd Spetsnaz Regiment, were instrumental in many wartime successes, most importantly the siege of Donetsk Airport (which 3rd Spetsnaz retook in a lightning strike back on May 26th, 2014), and now perform direct action and sabotage missions behind separatist lines. Navy special forces and combat divers are also involved in the war, especially in the southern port of Mariupol.
Lastly, there are the volunteer battalions, hastily organized in April 2014 to combat the Russian-backed insurrection, seeing as the army and police forces were largely demoralized and less than effective then. In time, these battalions grew into considerable fighting forces, even if of dubious effectiveness and even less discipline; while ostensibly created to combat insurgency, many are engaged in front-line combat against the pro-Russian paramilitaries, leading to several and disasters. The battalions, however, enjoy better publicity than the army and even the National Guard, sometimes being hailed as 'heroes' and 'patriots' by the more patriotic Ukrainians. Battalions nominally fall under the command of either the MVS (in which case they are typically called 'militsiya special battalions') or the MO (in which case they are called 'territorial defence battalions'), although the chain of command was... less than clear; battalion commanders had been known to act on their own initiative and disobey orders, leading to at least one major case of desertion. As of 2019, most of these units have now been absorbed into the National Guard, and the chain of command seems to to have been cleared up.
Most volunteer battalions have proper names and are typically associated with Ukraine's different regions and oblasts; the largest and best-known examples are the Donbass Battalion (one of the first ones to be formed) and Azov Battalion (notorious for being heavily associated with various Ukrainian far right organizations - as in, being comprised of the members of said organizations), named for the Donbass (Donets Basin) area and the Azov Sea respectively, or the Aidar Territorial Defence Battalion, so named for the Aidar River in the northern Luhansk oblast'.
From 2014-2015, the Ukrainian military was perhaps the only example of a crowdfunded military: due to being largely neglected for the past 23 years, the Armed Forces were suffering from a chronic lack of equipment, fuel, spare parts, medical supplies and even basic amenities. Inspired by the recent example of the Euromaidan revolution, Ukrainians from all over the country pitched in. Volunteers organized help, paying for supplies and logistics from their own money and donations to outfit the non-combat-ready units. Back in 2014, a drafted Ukrainian basically had to bring his own BD Us, helmet and body armor, as the Ministry of Defence (in charge of military supply and logistics) couldn't provide him with any. Volunteers supplied the army with firearm sights, thermal optics, radios and even unmanned recon drones. Volunteer efforts even restored a non-flightworthy An-26 aircraft to working condition in under five months. After grudgingly accepting civilian help, the Ministry of Defence finally relented and joined efforts with some more prominent volunteers, embarking on a campaign of structural and logistics reform which only starts to bear fruits. The volunteer movement is often cited as the only thing that saved Ukraine from inevitable doom, and turned Ukraine's army from an underfunded sham into a Badass Army which managed to hold back an enemy supplied by Russia's endless supply of military hardware.
Future of the Cossacks
As a result of reforms, crowdfunding, and consistent effort, Ukraine now has one of the biggest military forces in Europe outside of NATO; should NATO membership be granted it would be its largest national armed forces contribution outside the US. It has more than 10,000 women now in service, thanks to a Ministry of Defense decision in June of 2016 including women in the military, for a total of an estimated 400,000 active and 790,000 reserve personnel.
Since 2016, the professionalism and equipment of the army has been steadily improving too. Regular exercises are now held (often in conjunction with NATO), many aircraft have been repaired and restored to working order (with help from Poland), the navy has received a small force of gunboats, and Army was gifted powerful "Javelin" anti-tank missiles from the United States.
The Ground Forces (Sukhoputni Viyska)Biggest of the services with 300,000 active service personnel. Organized into 4 Operational Theater Commands and the 4th reserve corps.
The NavyActually de jure the youngest, born out of the 1997 division of the ex-Soviet Black Sea Fleet, but de facto active since its 1992 creation. But also the smallest. Was on the verge of being totally wiped out after 2014, when Russia seized most of the ships that weren't rusted into the harbor. It has since recovered somewhat with the delivery of about a dozens small combat boats, but two of these were lost in November 2018, when Russia attacked a Ukrainian convoy traversing the Kerch Strait (which is legally under dual sovereignty of Ukraine and Russia).
the Air ForceThe 36,300 personnel and 144 aircraft Air Force, based in Vinnytsia and one of the world's biggest air forces, is on a modernization plan following the Donbass conflict. Also has an active air defense command.
The Ukrainian military doesn't appear in fiction nearly as often as their Russian counterparts, but they can be expected to appear far more often than any other former-Soviet military (at least in works produced outside the former USSR). There are several reasons for this, first and foremost among them the simple fact that Ukraine has the second-largest population of the former-Soviet nations (after Russia) and the third-largest landmass (after Russia and Kazakhstan). Another factor is that Ukraine is one of the few nations of the former USSR other than Russia to maintain its own navy after the breakup of the Soviet Union, making them the obvious choice for naval-themed works requiring a former Soviet republic that isn't Russia for whatever reason.
- One of the protagonists in David Weber's near-future military science fiction alien invasion novel Out of the Dark is a Ukrainian soldier.
- Ukrainian forces appear in the STALKER series (the protagonist in S.T.A.L.K.E.R. Call Of Pripyat is an officer in the Ukrainian SBU, which is a law enforcement/intelligence agency, not part of the military).
- Appear as a playable side in Point of Existence 2, a total conversion mod for Battlefield2, which pits the ZSU against the Bundeswehr, of all people. How competent they are depends on the players, and the Ukrainians also spot some domestic equipment, such as T-84 Oplot Cool Tanks or the obscure Vepr bullpup derivative of the AK-74.
- Chernobyl Diaries: They quarantine the ruins of Chernobyl for the past 30 years or so and make sure anyone trespassing is properly disposed of, thus making their role as Armies Are Evil.
- Crysis 2 features the Grendel 6.8mm battle rifle, apparently Ukrainian-made. How and why it turned up in New York instead of any similar American-made battle rifle is uncertain at best.
- Command & Conquer: Red Alert allows the player to choose Ukraine as a faction in multiplayer mode. Obviously, the choice of buildings and units is the same as for the Soviet faction.
- In Lord of War, Villain Protagonist Arms Dealer Yuri is a Ukrainian-American whose parents fled the Soviet Union and settled in America. After the collapse of the USSR he returns to Ukraine and buys military hardware from the effectively unemployed Ukrainian Red Army troops.
- World War Z: The Ukrainian military tried to instill quarantine measures to evacuate its citizens to safe-zones but once the task proves too much to deal, they end up gassing civilians with Cold War chemical weapons to make sure who is infected with the zombie virus (which reanimates) to those who are clean (which do not reanimate). While described as an extremely controversial measure, it succeeds in defending the safe-zones in Ukraine including Crimea. Post-war, the Ukrainian military may face confrontation with the forces of the Holy Russian Empire for encroaching their territory.