South Korea and the United States conducted combined air drills, involving US B-52 strategic bombers and F-22 stealth fighters, on Tuesday. The drills were held win an effort to strengthen the credibility of America"s "extended deterrence," Yonhap cited Seoul"s Defense Ministry as saying. The drills took place in the South"s air defense identification zone southwest of its southern island of Jeju. The South"s F-35A stealth jets and F-15K fighters also joined the drills. American F-22 stealth fighters joined a Korea-US air drill near Jeju on Tuesday, as US strategic assets continue to rotate through the Korean Peninsula. The F-22 Raptors, which are returning to Korea for the first time in four years, flew in from an American air base in Okinawa, and joined US B-52H Stratofortress, a long-range subsonic strategic bomber, four Korean F-35 Lighting II stealth fighters and four F-15K Slam Eagles, multi-role fighters, for training. “The purpose of joint South Korea-US stealth fighter training is to strengthen the ability to respond to North Korea"s nuclear and missile threats,” a government source told the JoongAng Ilbo. “The training involves practicing strikes on North Korean high-value targets.” The F-22 is a fifth-generation fighter, considered the most advanced in operation. It is fast and stealthy and has highly sophisticated computing capabilities and avionics. They were originally scheduled to arrive last week but were delayed due to heavy snowfall in Korea. The last time F-22s were deployed to Korea was four years ago, when eight fighters joined a two-week joint air drill Max Thunder. The F-22s will be flying back to Kadena Air Base in Okinawa after joining another drill with the Korean F-35s this week. They will be deployed meanwhile at the U. air base in Gunsan, North Jeolla. The Defense Ministry said that the drill should contribute greatly to improving the interoperability of US-Korea combined operations in the air. “The deployment of US strategic assets, such as the B-52H and the F-22, is a result of the agreement between defense ministers of the two countries at the 54th ROK-US Security Consultative Meeting last month,” said a ministry official in speaking with the press on Tuesday.“The joint drill is a significant action to follow the strengthened extended deterrence pledge by the United States.” In the joint Security Consultative Meeting communiqué issued on Nov. 3, Seoul and Washington spelled out four linear categories — information sharing, consultation, joint planning and execution — as their extended deterrence cooperation against North Korea"s evolving nuclear and missile threat. North Korea has launched over 60 ballistic missiles this year, including an intercontinental ballistic missile on Nov. 18. Active movements detected near its nuclear test site have analysts warning of a possible nuclear test, which would be its seventh since the first in 2006. — Agencies