WASHINGTON (NYTIMES) - In the chaotic days leading to the death of Major-General Qassem Soleimani, 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 Donald 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.

Mr Trump initially rejected the Soleimani option on Dec 28 and authorised air strikes on an Iranian-backed Shi'ite militia group instead. But a few days later, the President watched, fuming, as television reports showed Iranian-backed attacks on the US Embassy in Baghdad, according to Defence Department and administration officials.

By late last Thursday (Jan 2), 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 US embassies, consulates and military personnel in Syria, Iraq and Lebanon.

Maj-Gen Soleimani 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, chairman of the Joint Chiefs of Staff, said last 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 scepticism about the rationale for a strike on Maj-Gen Soleimani, who was responsible for the deaths of hundreds of American troops over the years. According to one US official, the new intelligence indicated "a normal Monday in the Middle East" - Dec 30 - and Maj-Gen Soleimani's travels amounted to "business as usual".

That official described the intelligence as thin and said that Maj-Gen Soleimani's attack was not imminent because of communications the US had between him and Iran's supreme leader, Ayatollah Ali Khamenei, showing that the ayatollah had not yet approved any plans by the general for an attack.

The ayatollah, according to the communications, had asked Maj-Gen Soleimani to come to Teheran 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 oversee meetings and conference calls held by officials in the run-up to the strike.

Defence Secretary Mark T. Esper and Gen Milley declined to comment for this article, but Gen Milley's spokesman, Colonel DeDe Halfhill, said, without elaborating, that "some of the characterisations being asserted by other sources are false" and that she would not discuss conversations between Gen Milley and the President.

The fallout from Mr Trump's targeted killing is now under way.

On Saturday in Iraq, the US military was on alert as tens of thousands of pro-Iranian fighters marched through the streets of Baghdad and calls accelerated to eject the US from the country.

US 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 Maj-Gen Soleimani.

In Palm Beach, Florida, 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, he 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".

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, North Carolina, some 3,500 soldiers, one of the largest rapid deployments in decades, are bound for the Middle East.

Maj-Gen Soleimani, who was considered the most important person in Iran after Mr Khamenei, was a commanding general of a sovereign government. The last time the US killed a major military leader in a foreign country was during World War II, when the US military shot down a plane carrying Admiral Isoroku Yamamoto of Japan.

But administration officials are playing down Maj-Gen Soleimani'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 Maj-Gen Soleimani as too provocative.

Maj-Gen Soleimani 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.

Gen Milley and Mr Esper travelled last 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 US 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 Maj-Gen Soleimani, mainly to make other options seem reasonable.

Mr Trump chose strikes against militia groups. On Sunday, the Pentagon announced that air strikes approved by the President had struck three locations in Iraq and two in Syria controlled by the group Kataib Hezbollah.

Mr 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," Gen Milley told reporters last 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 US Embassy in Baghdad.

Mr Trump, who aides said had on his mind the spectre of the 2012 attacks on the US 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 US.

When Mr Trump chose the option of killing Maj-Gen Soleimani, top military officials, flabbergasted, were immediately alarmed about the prospect of Iranian retaliatory strikes on US troops in the region. It is unclear if Gen 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 Maj-Gen Soleimani, 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 Maj-Gen Soleimani at his expected arrival last Friday at Baghdad International Airport. If he was met by Iraqi government officials allied with Americans, one US 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 authorised the killing at about 5pm on Thursday, officials said.

Hours later, missiles fired from an American MQ-9 Reaper blew up Maj-Gen Soleimani's convoy as it departed the airport.