(CNN) The Trump administration is expected to announce the formal suspension of planning for major August multilateral military drills on the Korean Peninsula as soon as Thursday, according to several administration officials with knowledge of White House, State Department and Defense Department planning on how to carry out President Donald Trump's decision announced at the Singapore summit.

Detailed Pentagon guidance is expected this week on carrying out Trump's decision to suspend so-called "war games" with South Korea. The Pentagon's post-Singapore involvement in this issue is raising questions about whether the President sought military advice ahead of making his decision.

As the dust settles from the historic summit, some details about how Trump got the idea to offer a suspension of military exercises to North Korean leader Kim Jong Un are becoming clearer.

A source familiar with the matter pushed back on the idea that Trump got the idea to halt joint exercises from Russian President Vladimir Putin. The source said that, if anything, it's something that came from Chinese President Xi Jinping, who has been very vocal about it and has had direct conversations with Trump about the matter. The term "war games" was also a term coined by China and North Korea.

The source said halting the joint exercises was one of "many tools in the tool box" that the President took with him to meet with Kim but the final decision on what concession or concessions he would make wasn't determined until he was able to size up Kim. He told his top advisers before going in that he wanted to see where the meeting would go, and in the end he felt Kim was being genuine so he was willing to wheel and deal.

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