Identify moderate Syrian rebel groups, get them out of the country, train them, equip them, and send them back into the fight. That is supposed to be the West’s plan for combating the Islamic State inside its Syrian stronghold. What this strategy sacrifices in efficacy and directness it makes up for in its ability to forestall the introduction of Western combat troops into that hornets’ nest. But this was always going to be a tactical approach to the war in Syria that had a small window of opportunity, and that window may be closing.

The first band of anti-ISIS rebels in Syria to receive American weaponry recently suffered a catastrophic defeat at the hands of the al-Qaeda-linked Nusra Front. After losing control of their headquarters and the weaponry provided to them by Western powers, this Syrian moderate rebel group simply dissolved.

Nusra fighters boasted on Twitter that they had seized control of U.S.-made TOW anti-tank missiles and other American aid provided to Hazm when they overran the rebels’ headquarters in the town of Atarib in the province of Aleppo. The claims could not be verified, and American supplies of weaponry to moderate rebels in northern Syria had in any case been scaled back in recent months since the battles with Nusra began.

The collapse comes as the Pentagon embarks on a new effort to train moderate rebels to fight the Islamic State, a different extremist group that is at odds with Jabhat al-Nusra and has severed ties with al-Qaeda.

Hazm, which once claimed to have 5,000 fighters, had received U.S. weapons under a separate covert program launched last year by the CIA that was intended to bolster moderate rebels and put pressure on President Bashar al-Assad to compromise with the opposition.

Disheartening developments like these may explain why Syria’s former U.S. Ambassador Robert Ford performed an about-face on the matter of arming Syrian dissidents. In 2014, Ford resigned his post and issued a stinging condemnation of the Obama administration’s foot-dragging when it came to the conflict in Syria. Today, however, Ford is backing off his calls to arm moderate Syrian opposition groups. The former ambassador now insists that Syrian opposition forces are untrustworthy, increasingly friendly toward anti-Western insurgency organizations, and strictly on the defensive.

“We have to deal with reality as it is,” said Ford, who’s now with the Middle East Institute in Washington. “The people we have backed have not been strong enough to hold their ground against the Nusra Front.”

Ford today sounds like a different person from the optimist who only six months ago wrote an essay in Foreign Policy that began: “Don’t believe everything you read in the media: The moderate rebels of Syria are not finished. They have gained ground in different parts of the country and have broken publicly with both the al Qaida affiliate operating there and the jihadists of the Islamic State.”

Now, however, on panels and in speeches, Ford has accused the rebels of collaborating with the Nusra Front, the al Qaida affiliate in Syria that the U.S. declared a terrorist organization more than two years ago. He says opposition infighting has worsened and he laments the fact that extremist groups now rule in most territories outside the Syrian regime’s control.

It is apparent that the most effective anti-ISIS rebel group in Syria might be the Nusra Front, and some reports have indicated that these two Islamist militant organizations are engaging in a rapprochement. But with its al-Qaeda affiliations and support from benefactors in Qatar and Turkey, Nusra will never be a friend to the West. Ford, who observed that it is now impossible to field an effective counterinsurgency force of the size required to defeat ISIS in Syria even if there was uniform agreement in the West about what groups might constitute that force, has begun to concede that it is past time for Washington to consider American “boots on the ground.”

That was the last thing that the Obama administration wanted, and it is going to avoid reintroducing American combat forces into the Middle East at all costs. As a consequence of its paralysis, however, the Obama White House let the clock wind down and has let another period of advantage slip away in Syria. It is clear at this point that this administration’s Syria strategy is to hope this conflict remains relatively contained until the president can bequeath this mess to his successor.