Democrats are blaming President Donald Trump for inflaming tensions with Iran, while warning against another war in the Middle East amid reports military strikes by the U.S. were momentarily approved.

A senior administration official told The New York Times that the operation was under way in its early stages when it was called off.

On Friday, White House officials declined to comment on the Times' report. Defense Department officials hadn't commented Thursday night. No government officials asked The Times to withhold the article, the newspaper said.

A U.S. drone was shot down by Iran's Revolutionary Guard in "an unproved attack" in international airspace over the Strait of Hormuz on Thursday, U.S. Central Command has said. The commander of the Revolutionary Guard said the surveillance aircraft violated Iranian airspace and the country will not back down from threats.

In response to the mounting conflict, Democrats took aim at the decisions and diplomatic relations leading to the latest spat, including more American troops deployed to the region.

Sen. Elizabeth Warren, D-Mass., tweeted that Trump was failing on his promise to bring U.S. troops home and instead has "instigated another unnecessary conflict."

"There is no justification for further escalating this crisis — we need to step back from the brink of war," the presidential candidate said.

Warren pointed to the Trump administration's decision to pull out of the Iran nuclear deal as being a contributing element to the dispute. Sen. Brian Schatz, D-Hawaii, also pointed to the failed nuclear deal as the source of the crisis, tweeting Trump pulled out despite "the objections of anyone who knows anything about the Middle East or nuclear issues."

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The issue also made it to the Senate floor, with Sen. Tim Kaine, D-Va., warning against military action.

“I think another war in the Middle East now would be a disaster," Kaine said, while also calling for any funding of military action against Iran to require approval of Congress.

Going to war without a vote in Congress is deeply unfair to our troops. We're going to let Trump put them in harm's way while Congress hides under our desks, unwilling to put our names behind that war? We ask a lot of our troops. Let's honor them. — Tim Kaine (@timkaine) June 20, 2019

House Speaker Nancy Pelosi, D-Calif., told reporters that while Congress delivered its views on the conflict to the White House during a briefing on Thursday, Congress had not been consulted on military actions in the region.

"We make it very clear that in order to get engaged in any military activities we must have a new authorization of use of military force," she said, adding it remains unclear how future meetings with the White House will proceed.

Pelosi said she is confident that the American drone was operating legally in international airspace based on intelligence she received. But she also echoed caution in responding to the "untrustworthy adversary" that is Iran.

"How we go forward from here has to be strategic and smart," Pelosi said. "We know that the high tension wires are up there and we must do everything we can not to escalate the situation."

The U.S. has about 14,000 troops in Afghanistan, 5,000 in Iraq and at least 2,000 in Syria despite the Trump administration calling for a withdrawal from Afghanistan and Syria.