An F-22 Raptor flies in this undated image provided by Lockheed Martin.
Lockheed Martin via Getty Images
Also on Monday, South Korean President Park Geun-hye appeared to give her country's military permission to strike back at any attack from the North.
According to the New York Times, Park told the South's generals that she considers the threats from North Korea "very serious."
"If the North attempts any provocation against our people and country, you must respond strongly at the first contact with them without any political consideration.
"As top commander of the military, I trust your judgment in the face of North Korea's unexpected surprise provocation," she added.
NBC news had this detail about the deployment of the U.S. fighter jets:
"The U.S. military command in South Korea announced the deployment of the fighter jets in a statement.
"[North Korea] will achieve nothing by threats or provocations, which will only further isolate North Korea and undermine international efforts to ensure peace and stability in Northeast Asia," it said.
The exercise, called Foal Eagle, is meant to reinforce "the U.S. commitment of its most advanced capabilities to the security of the Republic of Korea," according to the statement.
The stealth aircraft were deployed to the Osan Air Base in South Korea from Japan to engage in bilateral military drills."
Last week, B-52 and B-2 stealth bombers were sent to South Korea for the annual exercise.