President Donald Trump authorized U.S. military strikes against Iran on Thursday, but officials abruptly pulled back from carrying them out just hours later, The New York Times reported.

U.S. military assets, including planes and ships, were in position during the early stages of the strike, ready to target several Iranian assets, the Times, citing senior administration officials, said. But those plans were called off before any missiles were fired.

The newspaper noted that it’s unclear if the scaling back of the plans reflected a change in opinion by the president or if there was a shift in strategy that necessitated they be delayed. It’s also unclear if they will go forward in the future.

In a series of tweets on Friday, Trump confirmed that the military had been “cocked & loaded” for an attack on Iran, but claimed that he was concerned about potential civilian casualties.

....On Monday they shot down an unmanned drone flying in International Waters. We were cocked & loaded to retaliate last night on 3 different sights when I asked, how many will die. 150 people, sir, was the answer from a General. 10 minutes before the strike I stopped it, not.... — Donald J. Trump (@realDonaldTrump) June 21, 2019

But in an interview on NBC’s “Meet the Press” later on Friday, the president said he in fact had not given final approval on any military strikes.

“Nothing was green-lighted until the very end because things change,” Trump said.

When Chuck Todd asked Trump if planes were in the air at any point before a strike was called off, the president responded: “No, but they would have been pretty soon, and things would have happened to a point where you would not turn back, you could not turn back.”

The White House did not respond to HuffPost’s request for comment.

Any initial approval of military action by Trump would reflect a significant uptick in tensions between Washington and Tehran. U.S. intelligence officials had reportedly been engaged in a heated debate over how to respond to a series of aggressive measures that have led to sky-high tensions between the two countries.

On Thursday, Iran shot down an unmanned American spy drone that was flying over the Strait of Hormuz. The Iranian government said the aircraft had flown into the country’s airspace, although President Donald Trump said the drone was “clearly” in international waters.

“We have it all documented,” Trump told reporters at the White House. “It’s documented scientifically, not just words.”

The president later said Iran had made “a very big mistake” in shooting down the drone.

Iran made a very big mistake! — Donald J. Trump (@realDonaldTrump) June 20, 2019

Any direct military action would dramatically heighten the conflict with Iran and its president, Hassan Rouhani. Last week, U.S. officials linked attacks on two oil tankers to Iran, saying the country was moving to consolidate control over a strategic shipping lane in the Persian Gulf (other nations have demanded more concrete evidence to support those claims). And earlier this week, Iran said it would soon have more stockpiles of low-enriched uranium than are allowed in a 2015 deal meant to curb the country’s nuclear program.

The pressure centers on Trump’s decision to withdraw the U.S. from the Iran nuclear deal, a hard-fought pact celebrated by many world leaders, including American allies, last year. The president had long derided the deal, declaring it “defective at its core” and “insane.”

The U.S. has since imposed many crippling sanctions against Iran.

The Times report is sure to increase political tensions in Congress, where a bipartisan coalition is building to demand that the White House seek congressional approval before taking military action.

“This is a dangerous situation,” House Speaker Nancy Pelosi (D-Calif.) said Thursday, according to The New York Times. “We are dealing with a country that is a bad actor in the region. We have no illusions about Iran in terms of their ballistic missile transfers, about who they support in the region and the rest.”

Antonia Blumberg contributed to this report.

This story has been updated with Trump’s tweets Friday morning and comments from his interview with “Meet The Press.”

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This article originally appeared on HuffPost.