Thomson Reuters
South Korean and US Marines take positions as amphibious assault vehicles from the South Korean Marine Corps fire smoke bombs during a joint landing operation drill in Pohang, South Korea.
Joint-training exercises with allied nations is nothing new to the US military. It reinforces relations between foreign powers and familiarizes them with each other's standard operating procedures in the event of a military conflict.
As one of these important allies, South Korea has trained with the US military for years to stabilize the Korean peninsula in case of a flashpoint crisis. Because North and South Korea are technically still at war, the US's presence is seen by many as a deterrent to a conflict with North Korea.
The two major drills - Foal Eagle and Key Resolve - will include, respectively, 11,500 US troops and 290,000 South Korean troops, and 12,200 US troops and 10,000 South Korean troops.
Although the drills were originally scheduled for March, it was postponed after North Korea resumed diplomatic relations with South Korea amid the 2018 Winter Olympics in Pyeongchang.
Unlike previous years where North Korea claimed the drills were a precursor to a military strike, North Korea's response to this year's exercises has been surprisingly muted.
The Pentagon reiterated that the drills had a "defensive nature," and that this year's version would be "at a scale similar to that of the previous years."
Check out the photos of the US and South Korean military in action: