President Donald Trump seemed to walk back his claim that the Islamic State group, also known as ISIS, has been totally defeated.

Trump on Thursday tweeted: "Russia, Iran, Syria & many others are not happy about the U.S. leaving, despite what the Fake News says, because now they will have to fight ISIS and others, who they hate, without us."

The day before, Trump claimed ISIS had been totally defeated as he defended his decision to abruptly pull roughly 2,000 US troops out of Syria.

President Donald Trump on Thursday seemed walk back his claim that ISIS, also known as the Islamic State Group, has been totally defeated, which he had cited a day before as the reason for his decision to abruptly pull US troops out of Syria.

Trump on Thursday tweeted that his decision to pull roughly 2,000 US troops out of Syria means other countries, including US adversaries, will have to continue the fight against ISIS.

"Does the USA want to be the Policeman of the Middle East, getting NOTHING but spending precious lives and trillions of dollars protecting others who, in almost all cases, do not appreciate what we are doing? Do we want to be there forever? Time for others to finally fight," Trump said.

He added: "Russia, Iran, Syria & many others are not happy about the U.S. leaving, despite what the Fake News says, because now they will have to fight ISIS and others, who they hate, without us. I am building by far the most powerful military in the world. ISIS hits us they are doomed!"

Read more: Trump declares victory over ISIS as the US prepares to pull all troops out of Syria

Russian President Vladimir Putin actually applauded Trump's decision to pull US troops out of Syria on Thursday.

"The fact that the US has decided to withdraw its troops is right," Putin said at an annual press conference.

The White House did not immediately respond for comment.

The decision to pull the US troops out of Syria was announced in an abrupt fashion on Wednesday, prompting confusion and alarm both in Washington and beyond.

By the end of the day, reports began to surface that US allies on the ground in Syria were caught by surprise as they expressed concern about how to confront ISIS on their own.

In announcing the decision to withdraw US troops from the Middle Eastern country on Wednesday, Trump tweeted: "We have defeated ISIS in Syria, my only reason for being there during the Trump Presidency." The president also tweeted a video in which he made similar claims.

But Trump's own agencies have hedged such a declaration for months.

Just a day before Trump declared ISIS was defeated, for example, State Department deputy spokesman Robert Palladino said of the fight against ISIS in Syria: "We've made significant progress recently in the campaign ... but the job is not yet done."

Read more: There are 4 winners in the US withdrawal from Syria — and they're all US adversaries

ISIS has lost its caliphate, or the vast swath of territory it once held across Iraq and Syria. But multiple reports, including one from the Pentagon inspector general, suggested the group still has between 20,000 to 30,000 fighters in the region.

"Getting rid of the caliphate doesn't mean you then blindly say, 'OK, we got rid of it,' march out, and then wonder why the caliphate comes back," Defense Secretary James Mattis told reporters at the Pentagon recently. "How many times have we seen — look at even Iraq where they're still on the hunt for them. And they're still trying to come back."

Read more: Trump just radically upended US Syria policy despite repeated warnings that doing so could be disastrous

Trump faced substantial criticism over the announcement to pull out US troops, including from fellow Republicans.

Republican Sen. Lindsey Graham, a close ally of the president, said it was "Fake News" to claim ISIS was defeated and said it was an "Obama-like mistake" to pull out US troops.

"To those who say we have defeated ISIS in Syria, that is an inaccurate statement. They have been hurt, they have been degraded, and I give the president all the credit in the world for changing our policies regarding the fight against ISIS, but I will not buy into the narrative that they have been defeated," Graham said in a speech on the Senate floor on Wednesday. "To say they're defeated is an overstatement and is fake news. It is not true. They have been severely damaged, but they will come back unless we're there to stop them."

US allies also criticized the decision.

"Much remains to be done and we must not lose sight of the threat they pose. Even without territory, Daesh (ISIS) will remain a threat," the UK's Foreign Office said in a statement on Wednesday.