WASHINGTON — In the chaotic days leading to the death of Maj. Gen. Qassim Suleimani, Iran’s most powerful commander, top American military officials put the option of killing him — which they viewed as the most extreme response to recent Iranian-led violence in Iraq — on the menu they presented to President Trump.
They didn’t think he would take it. In the wars waged since the Sept. 11, 2001, attacks, Pentagon officials have often offered improbable options to presidents to make other possibilities appear more palatable.
After initially rejecting the Suleimani option on Dec. 28 and authorizing airstrikes on an Iranian-backed Shia militia group instead, a few days later Mr. Trump watched, fuming, as television reports showed Iranian-backed attacks on the American Embassy in Baghdad, according to Defense Department and administration officials.
By late Thursday, the president had gone for the extreme option. Top Pentagon officials were stunned.
Mr. Trump made the decision, senior officials said on Saturday, despite disputes in the administration about the significance of what some officials said was a new stream of intelligence that warned of threats to American embassies, consulates and military personnel in Syria, Iraq and Lebanon. General Suleimani had just completed a tour of his forces in Syria, Lebanon and Iraq, and was planning an “imminent” attack that could claim hundreds of lives, those officials said.
“Days, weeks,” Gen. Mark A. Milley, the chairman of the Joint Chiefs of Staff, said on Friday, when asked how imminent any attacks could be, without offering more detail other than to say that new information about unspecified plotting was “clear and unambiguous.”
But some officials voiced private skepticism about the rationale for a strike on General Suleimani, who was responsible for the deaths of hundreds of American troops over the years. According to one United States official, the new intelligence indicated “a normal Monday in the Middle East” — Dec. 30 — and General Suleimani’s travels amounted to “business as usual.”
That official described the intelligence as thin and said that General Suleimani’s attack was not imminent because of communications the United States had between Iran’s supreme leader, Ayatollah Ali Khamenei, and General Suleimani showing that the ayatollah had not yet approved any plans by the general for an attack. The ayatollah, according to the communications, had asked General Suleimani to come to Tehran for further discussions at least a week before his death.
Secretary of State Mike Pompeo and Vice President Mike Pence were two of the most hawkish voices arguing for a response to Iranian aggression, according to administration officials. Mr. Pence’s office helped run herd on meetings and conference calls held by officials in the run-up to the strike.
Defense Secretary Mark T. Esper and General Milley declined to comment for this article, but General Milley’s spokeswoman, Col. DeDe Halfhill, said, without elaborating, that “some of the characterizations being asserted by other sources are false” and that she would not discuss conversations between General Milley and the president.
The fallout from Mr. Trump’s targeted killing is now underway. On Saturday in Iraq, the American military was on alert as tens of thousands of pro-Iranian fighters marched through the streets of Baghdad and calls accelerated to eject the United States from the country. United States Central Command, which oversees American military operations in the Middle East, said there were two rocket attacks near Iraqi bases that host American troops, but no one was injured.
In Iran, the ayatollah vowed “forceful revenge” as the country mourned the death of General Suleimani.
In Palm Beach, Fla., Mr. Trump lashed back, promising to strike 52 sites across Iran — representing the number of American hostages taken by Iran in 1979 — if Iran attacked Americans or American interests. On Saturday night, Mr. Trump warned on Twitter that some sites were “at a very high level & important to Iran & the Iranian culture, and those targets, and Iran itself, WILL BE HIT VERY FAST AND VERY HARD.”
The president issued those warnings after American spy agencies on Saturday detected that Iranian ballistic missile units across the country were at a heightened state of readiness, a United States official said on Saturday night.
Other officials said it was unclear whether Iran was dispersing its ballistic missile units — the heart of the Iranian military — to avoid American attack, or were mobilizing the units for a major strike in retaliation for General Suleimani’s death.
On Capitol Hill, Democrats voiced growing suspicions about the intelligence that led to the killing. At the White House, officials formally notified Congress of a war powers resolution with what the administration said was a legal justification for the strike.
At Fort Bragg, N.C., some 3,500 soldiers, one of the largest rapid deployments in decades, are bound for the Middle East.
General Suleimani, who was considered the most important person in Iran after Ayatollah Khamenei, was a commanding general of a sovereign government. The last time the United States killed a major military leader in a foreign country was during World War II, when the American military shot down the plane carrying the Japanese admiral Isoroku Yamamoto.
But administration officials are playing down General Suleimani’s status as a part of the Iranian state, suggesting his title gave him cover for terrorist activities. In the days since his death, they have sought to describe the strike as more in line with the killing of Abu Bakr al-Baghdadi, the Islamic State leader, who died in October in an American commando raid in Syria.
Administration officials insisted they did not anticipate sweeping retaliation from Iran, in part because of divisions in the Iranian leadership. But Mr. Trump’s two predecessors — Presidents George W. Bush and Barack Obama — had rejected killing General Suleimani as too provocative.
General Suleimani had been in Mr. Trump’s sights since the beginning of the administration, although it was a Dec. 27 rocket attack on an Iraqi military base outside Kirkuk, which left an American civilian contractor dead, that set the killing in motion.
General Milley and Mr. Esper traveled on Sunday to Mar-a-Lago, Mr. Trump’s Palm Beach resort, a day after officials presented the president with an initial list of options for how to deal with escalating violence against American targets in Iraq.
The options included strikes on Iranian ships or missile facilities or against Iranian-backed militia groups in Iraq. The Pentagon also tacked on the choice of targeting General Suleimani, mainly to make other options seem reasonable.
Mr. Trump chose strikes against militia groups. On Sunday, the Pentagon announced that airstrikes approved by the president had struck three locations in Iraq and two in Syria controlled by the group, Kataib Hezbollah.
Jonathan Hoffman, the chief Pentagon spokesman, said the targets included weapons storage facilities and command posts used to attack American and partner forces. About two dozen militia fighters were killed.
“These were on remote sites,” General Milley told reporters on Friday in his Pentagon office. “There was no collateral damage.”
But the Iranians viewed the strikes as out of proportion to their attack on the Iraqi base and Iraqis, largely members of Iranian-backed militias, staged violent protests outside the American Embassy in Baghdad. Mr. Trump, who aides said had on his mind the specter of the 2012 attacks on the American compound in Benghazi, Libya, became increasingly angry as he watched television images of pro-Iranian demonstrators storming the embassy. Aides said he worried that no response would look weak after repeated threats by the United States.
When Mr. Trump chose the option of killing General Suleimani, top military officials, flabbergasted, were immediately alarmed about the prospect of Iranian retaliatory strikes on American troops in the region. It is unclear if General Milley or Mr. Esper pushed back on the president’s decision.
Over the next several days, the military’s Special Operations Command looked for an opportunity to hit General Suleimani, who operated in the open and was treated like a celebrity in many places he visited in the Middle East. Military and intelligence officials said the strike drew on information from secret informants, electronic intercepts, reconnaissance aircraft and other surveillance tools.
The option that was eventually approved depended on who would greet General Suleimani at his expected arrival on Friday at Baghdad International Airport. If he was met by Iraqi government officials allied with Americans, one American official said, the strike would be called off. But the official said it was a “clean party,” meaning members of Kataib Hezbollah, including its leader, Abu Mahdi al-Muhandis. Mr. Trump authorized the killing at about 5 p.m. on Thursday, officials said.
On Friday, missiles fired from an American MQ-9 Reaper blew up General Suleimani’s convoy as it departed the airport.