As leaders around the world leapt upon the possibility of a diplomatic solution to the chemical weapons crisis in Syria - a solution prompted by an apparent gaffe by his Secretary of State - US President Barack Obama softened his line during a round of TV interviews in America.
The President had arranged interviews with all major US networks to drum up support for a military strike against Syria on Monday night, but earlier in the day Secretary of State John Kerry suggested during a press conference in London that a strike could be averted if Syria gave up control of its chemical stockpile to international control.
Within minutes Russia embraced the idea and even the Syrian foreign minister responded that it would consider the option. In turn the White House said it would take a “hard look” at the proposal, which was quickly backed by UN Secretary-General Ban Ki-moon and British Prime Minister David Cameron.
By the time he sat down for his round of TV interviews the possibility of a diplomatic solution was the first question the President faced.
He conceded that the idea of monitoring and ultimately destroying Syria's arsenal "could potentially be a significant breakthrough."
"I think you have to take it with a grain of salt, initially," Mr Obama said in an interview with NBC.
"We are going to run this to ground. We're going to make sure that we see how serious these proposals are."
Mr Obama told CNN's Wolf Blitzer the development was “positive if it is real.” But he said it was unlikely the possibility would even have arisen were it not for his threat of military action.
“I have to say that it's unlikely that we would have arrived at that point where there were even public statements like that without a credible military threat to deal with the chemical weapons use inside of Syria.
"If we don't maintain and move forward with a credible threat of military pressure, I do not think we will actually get the kind of agreement I would like to see."
But in his NBC interview he admitted he could lose a vote over military action in Congress.
“I wouldn't say I am confident,” he said.
Early in the day a CNN count of congressional support for a strike was 149 against, 44 for, with 320 undecided and 20 not responding. Most analysts believe that even if he could win over the Senate he would lose the vote in the House.
New polling shows opposition is hardening. In a CNN poll, more than seven in 10 Americans say such a strike would not achieve significant goals for the US and that it is not in the national interest for the country to get involved in Syria's civil war. A Washington Post-ABC News poll published on Monday afternoon shows rising opposition, with 64 per cent of Americans against a military strike against Syria, up five points from the previous week. Only 30 per cent support military intervention. Among Republicans, opposition to a military strike spiked by 16 points, to 71 per cent.
Mr Kerry's slip-up came during a press conference in London.
Asked if he could see any way for Dr Assad to stop a US air strike he said that if the Syrian leader immediately surrendered all his chemical weapons to international control he could avert military action.
“But he isn't about to do it, and it can't be done,” the Secretary of State added.
The State Department later said Mr Kerry's remarks were “rhetorical and hypothetical”.
But soon the idea gained support from Syria's key ally, Russia, which proposed that Syria place its chemical weapons under international control for their destruction.
"We have given our proposal to Syria's Foreign Minister Walid al-Moallem and are counting on a fast and, I hope, positive response," said Russian Foreign Minister Sergey Lavrov.
In turn Syria made a rapid, vague but positive response, telling the Russian Interfax news agency: “The Syrian Arab Republic welcomes the Russian initiative, motivated by the concerns of the Russian leadership for the lives of our citizens and the security of our country."
In turn the White House itself was soon reacting to the proposal, with the deputy National Security Adviser Tony Blinken telling reporters: "We would welcome a decision and action by Syria to give up its chemical weapons.
"We will take a hard look at the proposal," he said, adding that Syria's "track record to date, doesn't give you a lot of confidence.”
Then, at about 2pm Washington time, when former Secretary of State Hillary Clinton appeared at the White House to make pre-scheduled comments in support of the Obama administration's push for a military strike, she reflected the new diplomatic tone.
If Syria's government immediately surrendered its chemical weapons stockpiles to international control, "that would be an important step," she said.
"But this cannot be another excuse for delay or obstruction. And Russia has to support the international community's efforts sincerely or be held to account."
Mrs Clinton pressed the administration's case that Dr Assad had used chemical weapons in the ongoing civil war, killing 1400 people, and that the action demanded a strong international response lead by the US.
By mid-afternoon British Prime Minister David Cameron had chimed in, saying: “If Syria were to put its chemical weapons beyond use under international supervision, clearly that would be a big step forward and should be encouraged. I think we have to be careful though to make sure this is not a distraction tactic to discuss something else rather than the problem on the table. But if it's a genuine offer, it should be genuinely looked at."
Also, the UN General Secretary Ban Ki-moon backed calls for Syria to give up its weapons, saying: “I am considering urging the Security Council to demand the immediate transfer of Syria's chemical weapons and chemical precursor stocks to places inside Syria where they can be safely stored and destroyed."
The day had not begun with any overtures of peace. In an interview with CBS, parts of which were screened on morning television in America, Dr Assad had made veiled threats against the US. He said America should expect “every action” should it attack Syria, apparently suggesting his allies Iran and the militant group Hezbollah might strike back as well as his own regime.
“You have different parties, you have different factions, you have different ideology. You have everything in this region now," he said in an interview with CBS, apparently referring to his allies including Iran and the militant group Hezbollah.
He denied being a “butcher”, instead comparing himself to a surgeon.
"When you have a doctor to cut the leg to prevent the patient from the gangrene, you don't call him a butcher; you call him a doctor, and you thank him for saving lives," he said.
"When you have terrorism you have war, when you have war, you always have innocent lives that could be the victim of any war."