WASHINGTON — President Trump undercut his own Treasury Department on Friday with a sudden announcement that he had rolled back newly imposed North Korea sanctions, appearing to overrule national security experts as a favor to Kim Jong-un, the North Korean leader.

The move, announced on Twitter, was a remarkable display of dissension within the Trump administration. It created confusion at the highest levels of the federal government, just as the president’s aides were seeking to pressure North Korea into returning to negotiations over dismantling its nuclear weapons program.

“It was announced today by the U.S. Treasury that additional large scale Sanctions would be added to those already existing Sanctions on North Korea,” Mr. Trump tweeted. “I have today ordered the withdrawal of those additional Sanctions!”

The Treasury Department announced new sanctions on Friday against Iran and Venezuela, but not North Korea.