From the moment White House chief of staff John Kelly first informed him that dozens of people in Damascus had died choking and foaming at the mouth from another suspected gas attack, President Donald Trump was determined to strike back in Syria.
For him, the only question was how.
This was a sudden change of tune for a President who only a few days earlier had said he wanted to withdraw US troops from Syria's intractable civil war and, as he put it at an event in Ohio, "Let other people take care of it now."
But the images of last weekend's atrocities haunted Trump, White House officials said, triggering six straight days of tense deliberations with his newly-reorganised national security team - as well as coalition partners from France and the United Kingdom - over military options to retaliate against the alleged perpetrator he derided as "Animal Assad."
The result was 105 missiles raining down on three of Syrian President Bashar al-Assad's chemical weapons facilities on Saturday. The morning after, Trump tweeted - perhaps fatefully, considering former President George W. Bush's premature declaration of victory in Iraq - "Mission Accomplished!"
Even with Trump's jubilant response to the strikes, several advisers close to the President said they had no inclination there was a long-term strategy for the region - and he seems essentially in the same position now as he was after last April's attacks on Syria.
The missile strikes came at an especially traumatic moment. The commander in chief was increasingly agitated over the past week as legal and personal crises converged around him, exhibiting flashes of raw anger, letting off steam on Twitter and sometimes seeming distracted from his war planning.
As the military brass put together the final details on the Syria strike plan, for instance, Trump was following the New York court proceedings involving his personal lawyer, Michael Cohen, and was fixated on media coverage of fired FBI Director James Comey's new memoir.
The book paints a scathing portrait of the President's conduct in office and character, and Trump was personally involved in drafting the scorching statement attacking Comey that White House press secretary Sarah Huckabee Sanders read from her podium, according to a senior Administration official.
Saturday's surgical strikes were more restrained than the images Trump tried to conjure with his bellicose tweets previewing the action. Last Monday, he warned Assad and his government's backers, Russia and Iran, "Big price to pay." On Thursday, he wrote that missiles "will be coming, nice and new and 'smart!'"
But in closed-door national security meetings, the tone from top officials was decidedly more nuanced. Hanging over the discussions was concern that a US attack in Syria might provoke a conflict with Russia, which had threatened to retaliate.
The absence of a clear strategy in Syria complicated the discussions. Trump had campaigned as a non-interventionist and vowed to withdraw from Middle East entanglements that he decried as costing American lives and treasure.
And yet to Trump's national security team, action of some kind seemed to be a requirement, as officials said they listened to the President deride his predecessor, Barack Obama, for sometimes discussing possible military action and then not delivering it. At a White House dinner last Wednesday, Trump opined that the problems in Syria were caused "because Obama did not enforce his red lines," according to one attendee, Alan Dershowitz, a retired Harvard Law School professor.
Trump was insistent that the strikes impair the production of chemical weapons in Syria, and hoped that would prevent Assad from launching future attacks on his population, according to White House officials.
He wanted to inflict more damage than the largely symbolic air assault he ordered in 2017 on a Syrian airfield, which Assad's forces quickly repaired. Military officials said they took pains to present the options as larger than the last time, emphasising that the number of munitions used was roughly double.
As Trump said in announcing the strikes from the Diplomatic Room of the White House, "The purpose of our actions tonight is to establish a strong deterrent against the production, spread, and use of chemical weapons."
But as final options were presented, Trump was concerned about US missiles harming civilians. When chemical weapons storage and research facilities were established as the targets, officials said, Trump sought assurances that hitting stock piles might let off plumes that could injure or kill people who lived nearby.
Military officials said that they believe that no one - not even Syrian government personnel - was killed in the attack, which struck nonresidential facilities in the middle of the night.
While options for more expansive actions were also discussed, the plan that Trump ultimately endorsed, with a mix of air- and sea-launched missiles and sophisticated standoff airstrikes, was designed to minimise risk to US and allied personnel and lessen the chances of unwanted escalation, officials said.
National security adviser John Bolton, in his first week on the job, was a hawkish voice urging a meaningful show of force that would deter Assad. Trump also heard from some hawks on Capitol Hill, including Senator Lindsey Graham, who said he urged the President to forgo his plan to pull back troop levels in Syria.
"I fear when the dust settles this strike will be seen as a weak military response and Assad will have paid a small price for using chemicals yet again," Graham said.
Trump was characteristically impatient and wanted the military take action quickly, officials said, but Defence Secretary Jim Mattis and General Joseph Dunford, chairman of the Joint Chiefs of Staff, steered a more deliberative and careful process.
Mattis and Dunford articulated to Trump the risks involved with operating in Syria, including the possibility of escalation with Russia and Iran, or an unintended event that might drag the United States further into Syria's civil war, officials said.
"We were not out to expand this," Mattis told reporters just after the attack. "We were very precise and proportionate."
Military leaders calculated that retaliation from Syria or its allies could come immediately or in a harder-to-detect way, like the insurgent-style attacks that US forces had faced from Iranian-backed militias during the Iraq War.
Despite Trump's urgency to punish the Assad regime, the President allowed Mattis and his military leaders several days to coordinate an allied attack with the French and British, which the Pentagon argued would require naval maneouvers and target coordination among the three countries.
Military officials also said they needed time to develop the right targets. While officials had been watching known Syrian chemical sites on and off for years, aerial surveillance time has been dedicated mostly to other areas of Syria, where the United States and allied local forces continue to battle Isis. That meant the US military needed to refresh its intelligence on the chemical facilities before targeteers could build the "target packages" that would guide the operation.
As military leaders were busy plotting a strike plan in Washington, US Ambassador to the United Nations Nikki Haley emerged almost immediately as a voice of the Administration's outrage over Assad's suspected chemical attack - as well as over what she called Russian "disinformation" to protect its Mideast ally.
As Haley spoke alongside her counterparts from Britain and France, coordinating her remarks with theirs, Trump was on the phone with British Prime Minister Theresa May and French President Emmanuel Macron to forge a coalition.
Spending the week at the White House with a pared back public schedule, Trump was often distracted.
On Thursday, officials said, Trump awoke to learn on Fox News Channel that Russian officials had crowed that they could shoot down any American missiles fired on Syria. He vowed on Twitter, "Get ready Russia, because they will be coming, nice and new and 'smart!'"
Trump's apparent announcement of a missile attack surprised and rattled military leaders. Though the strategy talks were moving in the direction of military action, officials said, no decision had been made about whether, when or how to strike in Syria. It was not until Friday that military leaders presented Trump final options on targets.
As they prepared to initiate the strike, US commanders stepped up security measures for US troops across the Middle East, putting a US force of about 2000 inside Syria, on high alert.
Mattis for several days resisted concluding definitively that Assad's Government was responsible for the Douma attack, officials said, saying he had not seen enough evidence that the Syrian Government was responsible until last Friday.
But his boss did not share that apprehension. Even before a full intelligence briefing on the incident had been prepared, Trump assigned blame on Twitter last Monday.
"Many dead, including women and children, in mindless CHEMICAL attack in Syria," Trump tweeted. He added, "President Putin, Russia and Iran are responsible for backing Animal Assad. Big price to pay."