WASHINGTON — President Donald Trump froze at the controls.

After ordering up airstrikes on Iran in retaliation for the downing of an unmanned American drone, the commander in chief balked at the last minute Thursday.

"Nothing was green-lighted until the very end because things change," the president told NBC's Chuck Todd in an interview that will air on "Meet the Press" on Sunday, pointing to the expected casualty count as his reason.

"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 a 150 dead people that would have taken place probably within a half an hour after I said go ahead. ... I didn't think it was proportionate."

His indecision in the face of direct hostility from an avowed enemy brought a cascade of criticism from allies and political rivals, from Iran hawks and doves, and from a host of national security experts who asserted that it demonstrated weakness at a critical moment. And it left the world wondering whether Trump, who has so often questioned the leadership abilities of past presidents and candidates for his job, can handle a real crisis.

"Many of the Trump administration's weaknesses are coming home to roost," said Adam Ereli, a former U.S. ambassador to Bahrain during the Obama administration.

Ereli broke that down into five pieces: Trump spoke loudly but carried no stick; he hasn't built an international alliance to support a face-off with Iran; the absence of key permanent figures at the Pentagon and the National Security Council "severely limits" the ability of the government to "weigh options, plan for contingencies and execute effectively"; his domestic political calculations may play too big a role in his decision making; and the zig-zagging of his policy emboldens Iran while leaving allies uncertain.

"Trump is causing long-term damage to the credibility of America's commitment to its allies and regional security in this strategically vital part of the world," he said.

But the most stinging rebukes didn't come from former Obama officials or the field of Democratic presidential hopefuls who hope to oust Trump from office.

"Trump has given the impression he lost his nerve, when he should've responded swiftly but measuredly already a couple weeks ago," said Michael Makovsky, president of the Jewish Institute for National Security of America who was a senior aide to Defense Secretary Donald Rumsfeld in President George W. Bush's administration.

"President Trump's handling of rising Iranian provocations in the Persian Gulf is undermining American global credibility — the currency for foreign policy and the bedrock of deterrence — and our vital interests, as established at least since President Jimmy Carter in 1980," Makovsky said in a statement.

Even some of the president's political friends on Capitol Hill suggested he had choked in the clutch.

Four leading House Republicans — Minority Leader Kevin McCarthy of California, along with the top-ranking Republicans on the House Armed Services, Foreign Affairs and Intelligence committees — issued a joint statement calling on the president to stick to his guns, figuratively and literally.

"Iran directly attacked a United States asset over international waters," McCarthy, Texas Reps. Mac Thornberry and Michael McCaul, and California Rep. Devin Nunes said in the statement. "This provocation comes a week after they attacked and destroyed two commercial tankers in international waters. There must be a measured response to these actions."

In a series of tweets defending his decision Friday morning, Trump framed it as a minor hiccup in a policy designed to prevent Iran from acquiring nuclear weapons.

"I am in no hurry, our Military is rebuilt, new, and ready to go, by far the best in the world," Trump wrote. "Iran can NEVER have Nuclear Weapons, not against the USA, and not against the WORLD!"

Makovsky said Trump is misguided if his only red line is Iranian nuclear weapons development.