President Donald Trump took the U.S. to the brink of all-out war with Iran on Thursday night, then changed his mind at the last minute, according to a report from the New York Times.

After hours of meetings with senior administration officials and congressional leaders in the White House on Thursday evening, Trump pulled the trigger and approved attacks on a handful of Iranian targets like radar and missile batteries.

Then, with the planes already in the air and ships in position, but before any missiles were fired, Trump changed his mind and canceled the attack.

The account of what happened has been verified by numerous other media outlets, including the Washington Post, the Associated Press and Newsweek, but none of them has been able to clarify why Trump changed his mind.

However, on Friday morning Reuters reported that after green-lighting the attack, Trump made contact with Tehran, via an intermediary in Oman, to warn them that an attack was imminent unless Iran agreed to hold talks “about various issues.”

“He gave a short period of time to get our response, but Iran’s immediate response was that it is up to Supreme Leader [Ayatollah Ali] Khamenei to decide about this issue,” an Iranian official said.

“We made it clear that the leader is against any talks, but the message will be conveyed to him to make a decision,” a second Iranian official said. “However, we told the Omani official that any attack against Iran will have regional and international consequences.”

It is unclear if the threat of airstrikes against Iran remains, but regional U.S. military assets have been put on 72-hour standby, a Pentagon official told Newsweek. In another sign that the administration is viewing the situation in the region as volatile, it barred any American-registered aircraft from flying over Iranian-administered airspace.

Trump’s almost-attack on Iran was a response to the shooting down of a U.S. surveillance drone earlier on Thursday. Tehran claimed it was a defensive measure after the massive RQ-4 Global Hawk surveillance drone crossed into Iranian airspace.

On Friday, the commander of Iran’s Revolutionary Guard claimed that Tehran refrained from shooting down a Boeing P-8 military plane that he said was accompanying the unmanned drone, according to the Tasnim news agency. The plane, he claimed, had 35 people on board.

The last 24 hours have added significantly to tensions already present in the region: last week, the U.S. blamed Iran for a series of attacks against oil tankers in the Gulf of Oman. Earlier this week, Iran declared that it would exceed the limit for enriched uranium stockpiles before the end of the month, meaning it would breach the 2015 nuclear pact it signed with world powers.

The heightened tensions have raised concerns that the U.S. could become entangled in another military conflict in the Middle East.

Sen. Chuck Schumer (D-NY) told reporters after a meeting in the White House Thursday evening that “we’re worried that he and the administration may bumble into a war.” Schumer added that the Democrats stance is that Congressional approval is required to fund any conflict with Iran.

Republicans on Capitol Hill are attempting to frame Trump’s actions as calculated. “The administration is engaged in what I would call measured responses,” Senate Majority Leader Mitch McConnell said.

However, on Fox News on Thursday evening, Sean Hannity, whom the president is known to take advice from on occasion, was much less circumspect.

If Iran didn’t give in, Hannity said, Trump “will have no choice. He will bomb the hell out of them.”