The United States sent F-22 stealth fighter jets to South Korea on Sunday, March 31 to join military drills aimed at underscoring the U.S. commitment to defend Seoul in the face of an intensifying campaign of threats from North Korea, Reuters reported.

The advanced, radar-evading F-22 Raptors were deployed to Osan Air Base, the main U.S. Air Force base in South Korea, from Japan to support ongoing bilateral exercises, the U.S. military command in South Korea said in a statement that urged North Korea to restrain itself.

"(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," the statement said.

The F-22 jets will take part in the annual U.S.-South Korea Foal Eagle military drills, which are designed to sharpen the allies' readiness to defend the South from an attack by North Korea, the U.S. military said.

The U.S. military did not say how many of the planes were flown to South Korea from Kadena Air Base in Okinawa. The statement described Sunday's deployment as part of routine shifts of air power among bases in the Western Pacific that U.S. forces have been conducting since 2004.

The two Koreas have been technically in a state of war since a truce that ended their 1950-53 conflict. Despite its threats, few people see any indication Pyongyang will risk a near-certain defeat by re-starting full-scale war.