Here are incredible photos of the military drill that's freaking out North Korea

The operation involves 12,500 US troops, along with an astonishing 200,000 of their South Korean counterparts.

Because Foal Eagle takes place in South Korea, North Korea views it as a possible practice run for an invasion. Pyongyang has ratcheted up the rhetoric and has threatened that Foal Eagle 2015 would be greeted with a "merciless baptism by fire."

In response to the start of Foal Eagle, North Korea launched two SCUD missiles into the sea outside of South Korea on March 2. On March 12, North Korea fired an additional seven surface-to-air missiles to protest against the exercise.