For a moment, let's ignore how hypocritical and childish Koko's ideals are here. Or that activating this system would kill more lives than it would save. Or that the moment other countries found out about it, it and Koko would become the biggest target in the world (and even she can't take on the entirety of mankind). My question is: how could the Jormungand System possibly assure world peace simply by removing air travel? And even if that weren't the only thing it did, how could it stop humans from being a race that fights itself? Even if she put mankind into the stone age, they'd just use sharp stones and their bare hands.
Kaspar makes the exact same points to Koko in the final episode.
The BIGGER head scratcher is how Jormungand could possibly work as advertised (cut mankind off from air travel). Even IF it has the ability to hack modern aircraft using digital communications and GPS navigation...how would it hack an airplane that didn't have a computer on it? Or a plane that had a computer that didn't have a connection to the network Jormungand was on? If a plane has no inputs to receive the hack commands to crash, how will Jormungand make the aircraft crash? Magic? It's not like you're even limiting aircraft's offensive weaponry that much. The laws of physics are still the same, so missiles and bombs can still be guided based on heat, radar, or laser guidance. Did Koko kill 700,000 people to deny the world the right to GPS guided weapons?
Note that it's also not explained how in hell it's supposed to prevent missile warfare (up to, and including ICB Ms). Missiles were born quite before GPS, the latter just gave some of them a terrifying accuracy. I got a feeling that the story originally included a subplot about hooking world's military on to some global information carrier, and only then going with the "hack them all" plan - but for some obscure reason the author decided to drop out that subplot completely.
But wait, there's more! The US, Russia, and China have all demonstrated the ability to shoot down satellites in orbit. There's no particular reason that Jormungand can't just be dismantled. Even if it's left in place, there's no reason to believe that it's going to be effective for much. Now that everyone knows that wireless communication is insecure, the armed forces of the world will probably just revert technologically a bit. We didn't have the internet or GPS back in the 1940's, and that didn't do much to slow down World War II. In the best case scenario, all Koko has really accomplished is to revitalize the postal service. More likely, she kicked off World War II.
Why the heck does anyone believe Koko for a second that she wants world peace, when she shows time and again that she's a megalomaniac and possibly insane person who just wants power? Not to mention world peace would essentially drive her business down to nil. It honestly comes off like she's just flat out lying to everyone and just sees the entire thing as a way for her to get even more power.
Why, with a clear shot at both Orchestra assassins, did a veteran soldier who had a suppressed weapon and demonstrated accuracy with it, not kill them both? Lehm was standing BEHIND both, and instead stands around calling in heavier weapons and directing team members to better positions. The entire episode 3 gunfight made me groan aloud.