The Trump administration has agreed to delay joint military exercises with South Korea until after the Pyeongchang Winter Olympics next month, the Pentagon said on Thursday.

The decision pushes back a set of annual military exercises known as Foal Eagle, which normally are held between February and April.

The decision came as President Donald Trump on Thursday attempted to take credit for the possible reopening of talks between Seoul and Pyongyang, in a departure from his previous skepticism over dialogue.

He tweeted: "Does anybody really believe that talks and dialogue would be going on between North and South Korea right now if I wasn’t firm, strong and willing to commit our total 'might' against the North," adding that "talks are a good thing!"

It also came as Japan's Prime Minister Shinzo Abe said on Thursday that North Korea's missile and nuclear weapons programs are "the most serious threat for our national security since the end of World War II." He promised to carry on building up Japan's military to help protect the nation.

The US decision to delay provocative military exercises also came as it was reported that North Korea accidentally misfired a test ballistic missile into one of its own cities in April last year.