WASHINGTON (AP) - President Donald Trump said Friday he abruptly called off the swiftly planned military strikes on Iran because the likely deaths of 150 Iranians would have been so out of proportion to the shootdown of an unmanned American surveillance drone. He also indicated he still hopes for talks with Iranian leaders rather than any escalation of military conflict.

"I am in no hurry," he wrote on Twitter, adding that increasingly severe sanctions meant to push Iran to the nuclear negotiating table are "biting" the Iranian economy.

The aborted attack was a stark reminder of the potential for the escalating tensions of the past year between the U.S. and Iran to lead to full-scale conflict, even as the president repeatedly insists he does not want war and wants to negotiate with the Islamic Republic over its nuclear program.

Iran on Friday showed no public inclination to negotiate, and it was unclear whether Trump, who said the U.S. military had been "cocked and loaded" to hit Iran, was considering new military options. After Iran downed a huge Navy surveillance drone over the Strait of Hormuz, Trump alternately denounced it as a "big mistake" and dismissed it as a "fly in the ointment."

Iran insisted the U.S. drone violated Iranian airspace; Washington said it had been flying over international waters when it was hit by an Iranian missile. Iran said it recovered debris in its waters. The U.S. military said Friday that although debris from the destroyed drone was spread across a wide area, none had yet been recovered by American forces, who were encountering high winds and heavy seas.

In a television interview, Trump said the U.S. was within 10 minutes of conducting strikes against Iran on Thursday when he canceled the operation. He told NBC News that he never gave a final order - planes were not yet in the air but would have been "pretty soon."

He said military officials came to him about 30 minutes before the strikes were to be launched and asked him for his final approval. Before signing off, he said he asked how many Iranians would be killed and was told approximately 150.

"I thought about it for a second and I said, 'You know what? They shot down an unmanned drone, plane - whatever you want to call it - and here we are sitting with 150 dead people. That would have taken place probably within a half an hour after I said go ahead. And I didn't like it. I didn't think it was proportionate."

Trump's assertion that he learned only at the last minute of his military advisers' casualty estimate does not align with the usual way a president is briefed on military attack options. An assessment of the likelihood of casualties, whether civilian or military, and a broad estimate of the number, normally are a major element of each option provided to the commander in chief.

Iran addressed the subject of casualties, too. Gen. Amir Ali Hajizadeh, the head of the Revolutionary Guard's aerospace division, said Friday that a U.S. spy plane with around 35 crew members was flying close to the unmanned U.S. Navy RQ-4A Global Hawk that was shot down, but that Iran chose not to target the manned aircraft. He said Iran warned the drone several times before downing it with a missile.

The president's decision to call off the attack is a reminder that despite the escalation in tensions between Washington and Tehran in recent weeks, there is a realization that military action, once under way, can quickly lead to unintended consequences, including large-scale war.

Asked how he was weighing his options, Trump said in a meeting with congressional leaders Thursday, "My gut," according to a person familiar with the exchange.

Trump has said repeatedly he does not want war with Iran, but he has offered little insight to his strategy, beyond inviting Iran's leaders to call him to reopen nuclear negotiations.

His administration last year pulled out of the 2015 international agreement intended to curb the Iranian nuclear program, an agreement he strongly criticized as ineffective during his presidential campaign. He demanded negotiations for a new agreement, but there have been none. Pressuring Iran, he launched a campaign of increasing economic pressure against the Islamic Republic, including cutting off its oil export revenues.

The current crisis comes at a tumultuous moment at the Pentagon, where the acting secretary of defense, Patrick Shanahan, is stepping down this weekend. Mark Esper, the civilian head of the Army, will take over on an interim basis on Monday and will fly to NATO headquarters in Brussels for meetings this week to discuss the way ahead on Iran.

Katie Wheelbarger, a senior Pentagon policy adviser on international security, said Friday the administration wants to keep the allies informed, including on the intelligence information that prompted the U.S. to send an aircraft carrier and other military assets to the Gulf region in early May in response to what it called heightened Iranian threats.

"It's very important to the (defense) department and the U.S. government as a whole that we make sure our allies are as cognizant, and that we are as transparent on this issue as possible," she said.

Although top congressional leaders met with Trump at the White House on Thursday to discuss Iran, he apparently did not tell them an attack was imminent. House Speaker Nancy Pelosi said Friday she and her colleagues were left with the impression that Trump was considering his options.

"I didn't receive any heads-up that there was that strike that was in the works," Pelosi said.

Democrats made the case for caution, for partnering with allies, and for taking a breath to de-escalate.

Rep. Adam Schiff of California, chairman of the House intelligence committee and a frequent Trump critic, said, "I don't think that people should be jumping down the president's throat for wanting to think this through and make sure that neither side miscalculates and we don't inadvertently end up in a war with Iran."

"It is also very important for the administration to understand ... that there is no congressional authorization to go to war with Iran."

For some, like House Armed Services Committee Chairman Adam Smith, D-Wash., Thursday was his first meeting with Trump.

Smith said he asked those around the table - who included all of Trump's top national security officials:

"You got a maximum pressure campaign on Iran, and what you want is you want Iran to say, 'OK, we give up.' OK, I get that, but that's unlikely. Iran is more likely to do what they've done, and what are you planning on doing when they do?"

They didn't have an answer, he said.

Smith's remarks reflect widespread skepticism at home and abroad over the administration's approach to Iran.

Rep. Hank Johnson, a Georgia Democrat and member of the House Armed Services Committee, said, "The president appears to be making decisions by the seat of his pants, impulsively."

Trump, in his lengthy morning tweet, defended his stance on Iran. He said he pulled out of the 2015 nuclear deal, which gave Tehran sanctions relief in exchange for pledges to rein in its nuclear program, because the agreement only temporarily blocked Iran from having nuclear weapons. Trump said the deal also did not stop Iran's support of militant groups or restrain its ballistic missile program.

He said his exit from the deal and the re-imposition of sanctions on Iran has crippled its economy.

"Now they are Bust!"

"I am in no hurry," he said. "Sanctions are biting & more added last night."