America raised the B-1B bomber; "Retribution follows"

South Korea's Defense Ministry said the exercise was aimed at demonstrating joint deterrence capabilities in light of North Korea's advancing nuclear program, AP reported.

The US and South Korea regularly conduct joint military maneuvers that they describe as defensive, while Pyongyang considers these activities "preparation for an invasion."

"The recent military action by the US and the Republic of Korea is an open threat to the security of our country and a serious provocation that raises military tensions in the region to an extremely dangerous level," said an unnamed spokesman for the North Korean Ministry of Defense, state media reported.

North Korea has said that it will "deter American aggressive attempts" with strong means and that this will harm the security of America itself.

US President Donald Trump has repeatedly praised his personal relationship with North Korean leader Kim Jong Un.

In late March, Trump called Kim a "very smart man" and said there was communication between the two countries, although Pyongyang has not responded publicly and no official talks are established.