U.S. President Donald Trump on Friday, June 21 morning said the U.S. was "cocked and loaded" to respond militarily against Iran for the downing of a U.S. drone earlier in the week, but said he called off the operation moments before it was to begin because such a move wouldn't have been proportional, CNN reports.

"I asked, how many will die. 150 people, sir, was the answer from a General. 10 minutes before the strike I stopped it, not ... proportionate to shooting down an unmanned drone. I am in no hurry," Trump said in a series of tweets, adding that the U.S. was eyeing three targets and vowing that Iran can "NEVER" have nuclear weapons.

The United States remains locked in a standoff with Iran, with U.S. military or diplomatic responses having the potential to provoke further escalation from Tehran. Iran's downing of the drone earlier Thursday has left the President caught between Republicans demanding a response and congressional Democrats warning that Trump -- and the Iran policy hardliners on his national security staff, who welcome the confrontation -- could lose control of the situation and lead the U.S. into war.

The U.S. military targets were a limited set of Iranian radars and missile batteries, said a U.S. official with direct knowledge of the matter, who spoke on the condition of anonymity because of the sensitivity of the information. No U.S. weapons had been launched when the decision was made to call off the strikes, which were first reported by The New York Times.

Military and diplomatic officials were expecting a strike as late as 7 p.m. ET on Thursday after intense debate among Trump's top national security officials and congressional leaders at the White House, multiple senior administration officials involved in or briefed on the deliberations told the Times. The strike had been scheduled for just before dawn on Friday in Iran to minimize the risk to civilians and the Iranian military, and military officials received word shortly after then that the strike was off, at least temporarily, the Times reported.

On Friday, Seyed Abbas Mousavi, a spokesman for Iran's Foreign Ministry said his country "responds to diplomacy with diplomacy, respect with respect, and to war with decisive defense."