Trump’s acknowledgement that he had given sensitive information during a White House meeting last week undercut intense efforts by senior aides to play down the incident on Monday evening, after news reports emerged of Trump’s conversations about a planned ISIS operation.

The president took to Twitter on Tuesday to defend his actions in the face of intense criticism, including from some of his fellow Republicans.

Two U.S. officials said Trump shared the intelligence, supplied by a U.S. ally in the fight against the militant group, with Russian Foreign Minister Sergei Lavrov and Russian Ambassador Sergei Kislyak during an Oval Office meeting last Wednesday.

The disclosures roiled the administration as it struggled to move past the backlash over Trump’s abrupt firing on May 9 of FBI Director James Comey, who was investigating potential ties between Russia and Trump’s 2016 presidential campaign.

Russia has denied such meddling, and Trump bristles at any suggestion he owed his Nov. 8 victory to Moscow.

“As President I wanted to share with Russia (at an openly scheduled W.H. meeting) which I have the absolute right to do, facts pertaining to terrorism and airline flight safety,” Trump said on Twitter. “Humanitarian reasons, plus I want Russia to greatly step up their fight against ISIS & terrorism.”

A U.S. president has the authority to disclose even the most highly classified information at will, but multiple U.S. and allied officials told Reuters that Trump had endangered cooperation from an ally that has some intelligence on ISIS.

In his tweets, Trump did not dispute media reports, initially from The Washington Post, that he revealed details that could jeopardize intelligence capabilities.

That appeared to put him at odds with members of his own senior staff. Secretary of State Rex Tillerson and National Security Adviser H.R. McMaster denied on Monday that Trump had revealed intelligence sources and methods or military operations at the Russia meeting.