US President Donald Trump has tweeted that he reversed a decision to slap new sanctions on North Korea – a move that has left officials scratching their heads.

Mr Trump delivered the news from his private club in Palm Beach, Florida, writing, “It was announced today by the US Treasury that additional large scale Sanctions would be added to those already existing Sanctions on North Korea. I have today ordered the withdrawal of those additional Sanctions!”

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. I have today ordered the withdrawal of those additional Sanctions!

— Donald J. Trump (@realDonaldTrump) March 22, 2019

The problem: The Treasury did not announce any new action affecting North Korea on Saturday (AEDT), let alone “additional large scale Sanctions.”

The administration on Friday (AEDT)  did sanction two Chinese shipping companies suspected of helping North Korea evade sanctions – but not the country itself.

So what was Mr Trump referring to? The White House wouldn’t say.

Press secretary Sarah Sanders issued only a brief statement saying that Mr Trump “likes” North Korean leader Kim Jong-un and “doesn’t think these sanctions will be necessary”.

But a person familiar with the action later told The Associated Press that Mr Trump’s tweet was not about reversing existing sanctions.

Instead, the person said, the president was talking about not going forward with additional large-scale sanctions on North Korea at this time.

The person was not authorised to discuss the president’s comments and spoke on condition of anonymity.

It was the latest example of the confusion sometimes sparked by Mr Trump’s governance-by-tweet, which has often sent agency heads scrambling, trying to figure out what he meant or trying to implement policy proclamations that have not gone through traditional vetting processes.

That includes when Mr Trump announced, via Twitter, that transgender people would no longer be allowed to serve in the military.

Mr Trump’s tweet took Treasury officials by surprise and prompted reporters to bombard officials at the White House National Security Council and Treasury Department with questions.

All declined to comment.

The reversal came a day after the Treasury Department announced the first targeted actions taken against Pyongyang since Mr Trump and Mr Kim met in Hanoi, Vietnam, last month for negotiations about North Korea’s nuclear weapons program.

-AAP