It's suddenly become very lonely at the front.
When President Hollande announced immediately after the August 21 attack near Damascus that France would "punish" the Assad regime, he was certain France would be acting alongside Britain and the United States.
The British parliament's surprise veto of military action upset all that.
Unlike David Cameron, whose executive powers are limited by Britain's parliamentary system, Barack Obama was under no obligation to seek the approval of Congress for air strikes.
But, unsettled by the British defection, this is exactly what he has done.
Now, as the world waits to see whether American lawmakers will vote the same way as their British counterparts, France is left in the uncomfortable situation of the schoolboy who's been talking big in the playground only to find that the two big mates who were backing him up have disappeared.
In an interview with "Le Figaro" newspaper on Tuesday, Bashar al-Assad said of any possible military action, "There will be repercussions - negative ones obviously - for the interests of France."
French intelligence reported on Monday that an attack using "massive amounts of chemical agents launched near Damascus on August 21 could not have been carried out by anyone other than the Syrian government."
Assad claimed in Tuesday's interview that his government was not responsible, that Syrian government forces were among the injured and that it would have been “illogical” for the government side to have carried out the attack.
French air strikes "would ignite a powder-keg" in the Middle East, Assad said.
This is a decisive moment for French foreign policy.
Syria is, after all, one of those large parts of the world that used to be colored blue on French maps; with Lebanon it was part of a French protectorate from 1918 to independence in 1943.
Loath to commit to military intervention, France, like the United States, nevertheless told Assad it would attack him if he used chemical weapons. It was a line the Syrian dictator must not cross.
Does France have the means to go it alone? Hollande, like Obama, has said the military response must be "proportionate" - by which he means a short series of punitive air strikes.
In the Rafale fighter bomber, Hollande has at his fingertips what the French believe to be the best jet fighter in the world. France possesses an aircraft carrier, the Charles De Gaulle, and a major military base in Djibouti.
Over the last few years, France has reminded the world that it is one of the few countries willing and able to launch military operations - alone if necessary.
In Libya, the French navy and air force took the leading role in the Franco-British coalition that led to the overthrow of Colonel Moammar Gadhafi. In Mali, it was French forces - and French forces only - that last year liberated the north of that country after a takeover by Islamist extremists.
'France cannot act alone'
Now, in the face of the defiance of Damascus, not to strike would be seen by many as a humiliating climb-down.
But this is what France seems to be preparing to do.
Interior Minister Manuel Valls said on Europe 1 radio that President Hollande's "determination remains the same" but that "France cannot act alone."
The country does not have the means to do so, he claimed. "We need a coalition. We are bound to wait" for the result of the vote of the US Congress, he said.
On Tuesday, French lawmakers debated the French riposte in the National Assembly, but it was a debate without a vote.
In France, as in the US, the executive does not need a green light from the legislature in order to take military action.
Francois Hollande is the commander in chief of the French armed forces, and it is ultimately up to him. But, if France does climb down, it may yet take the same road as Obama.
Speaking on RTL on Wednesday, Minister for Relations with Parliament Alain Vidalies said giving the parliament a vote and, with it, the possibility of a veto "was not a taboo for Hollande."
Not a taboo, perhaps, but it would completely alter the balance of power of the very presidential Fifth Republic set up by General De Gaulle in 1958.
'It's our fault…'
However, pulling back from military action would be popular in the country.
As in the United States, opinion polls show a clear majority of people do not think France should get involved.
And this position has not changed despite the shocking images of chemical weapons injuries that have been shown on French television.
Out on the streets of Paris, one woman said air strikes would only "add more horror to the horror. What do you think [military action] would achieve?"
"It's our fault," said one man. "We've spent so much time mocking Hollande, saying he's soft and so on that now he wants to prove he's tough."