Pelosi, in statement: "This morning, I spoke to the Chairman of the Joint Chiefs of Staff Mark Milley to discuss available precautions for preventing an unstable president from initiating military hostilities or accessing the launch codes and ordering a nuclear strike."

Pelosi goes on: "The situation of this unhinged President could not be more dangerous, and we must do everything that we can to protect the American people from his unbalanced assault on our country and our democracy."

Update: via @TBowmanNPR, Gen. Milley has now issued a statement. "Speaker Pelosi initiated a call with the Chairman. He answered her questions regarding the process of nuclear command authority.”

The military can't refuse a direct order by proper civilian authority. We'd never want them to. But they need not follow an illegal order. They can push back on unwise orders. They also can (and, at times, have) said: Mr. President, it will take us some days to prepare for that.

However, the statement from Milley's spokesman is only the two sentences quoted above, confirming that a call happened and that Milley explained the current command process.