The U.S. and South Korea are conducting high profile naval exercises near the South Korean coast on the 57th anniversary of the armistice that ended the Korean War.
The naval exercises are designed to show the U.S. commitment to South Korean security.
"We need to demonstrate at all times to our friends and potential foes that the United States remains completely committed to the Asia-Pacific region during this incredibly dynamic period," Assistant Secretary of State Kurt Campbell said.
8,000 thousand U.S. and South Korean sailors are involved in the exercise.
The drills come just four months after North Korea's torpedo attack on a South Korean warship which killed 46 sailors. It was the worst attack on South Korea since the Korean War.
North Korea is against the drills and has promised what it calls a "physical response."
The commanding officer of the USS Curtis Wilbur said the exercises have been a success.
"It's a show of force, a deterrent," Captain Paul Hogue said.