WASHINGTON (NYTIMES) - President Donald Trump has ended the clandestine American programme to provide arms and supplies to Syrian rebel groups, US officials said, a recognition that the effort was failing and that the administration has given up hope of helping to topple the government of President Bashar Assad.
The decision came more than a month ago, the officials said, by which time the effort to deliver the arms had slowed to a trickle.
It was never publicly announced, just as the beginnings of the programme four years ago, were officially a secret, authorised by then President Barack Obama through a "finding" that permitted the CIA to conduct a deniable programme. News of the troublesome programme soon leaked out.
It joins similar failed efforts to deliver arms and money to groups seeking to overthrow governments that Washington found noxious, most famously the Kennedy administration's disastrous effort to do away with the government of Fidel Castro in Cuba.
The White House had no comment. But the decision is bound to be welcomed by the Russians, whose military has backed Assad's government and relentlessly attacked some of the rebel groups that the US was supplying, under the guise of helping to eradicate terrorists.
On Tuesday, Iran's foreign minister, Mohammad Javad Zarif, charged that the US had helped destabilise the region, and portrayed Iran as merely defending its interests. Washington, instead, views Iran's aid to the Assad government as part of an effort to restore itself as a major regional power.
From the start, there were doubts that arming disorganised, often internally fractious forces would succeed. Officials in the Obama administration conceded that there was no way to predict the future loyalties of those who received US arms, despite a lengthy vetting process. That problem - getting the weapons into the right hands and assuring they were not passed on to others and used against US troops or allies - plagued the effort soon after it was proposed by Hillary Clinton, who was then secretary of state, and David Petraeus, the CIA director at the time.
Trump's decision was first reported by The Washington Post. But it was foreshadowed as early as April, when the Trump administration said that ousting Assad, whose government has fought a civil war that has taken roughly half a million lives, was no longer a priority. Instead, the US and Russia have been discussing cease-fire zones in the country, the first of which went into effect this month.
Those discussions have been possible because Assad, secure in his support from Moscow and Teheran, no longer sees a fundamental threat to his ability to remain in power. And Trump's decisions amounted to an acknowledgment that no escalation of the programme, which began in 2013 in concert with the CIA's counterparts in Saudi Arabia, Turkey and Jordan, was likely to yield a different result.
When it began, the initial objective was to force Assad to the bargaining table, in a series of negotiations that then secretary of state John Kerry took up in earnest in late 2015. But each agreement - for cease-fires, and deadlines for a political "road map" for elections in the country - fizzled.
Kerry fumed that Obama was not willing to provide the kind of military pressure on Assad that might bolster the diplomacy. Obama, for his part, was leery of entering another Middle East war whose outcome he could neither control nor predict.
The programme became less relevant as the Russians increased their presence in Syria, targeting and badly weakening the CIA-backed rebels, who were the most capable of the opposition fighters. That helped the Assad government claw back and consolidate territorial gains.
"This is a big deal, but it's been a long time coming," Charles Lister, a Syria analyst for the Middle East Institute in Washington, said. "It's the biggest indication so far of the administration's having given up on the opposition."
"After all, the Southern Front has consistently been our most reliable anti-Assad partner," Lister said, referring to opposition forces fighting Assad in the southern part of the country. "It's also the result of strong Jordanian pressure, as Amman has been pushing a freeze for a long time. So it was probably inevitable, but it's nonetheless very significant."
He added that it was "a big mistake in my mind". Other independent experts said it was unclear whether Trump's decision would impact fighters defending areas held by the opposition.
At its height, the programme was run through operations rooms in Jordan and Turkey, supporting rebel groups fighting under the banner of the Free Syrian Army who were deemed not to be extremists.
But the pressure on Assad was not great enough to force him to enter negotiations to end the civil war. Nor was it sufficient to clear the way for the rebel groups to take over major cities or approach the capital, Damascus. The programme also sought to bolster so-called moderate rebels against extremist factions such as the Syrian affiliate of al-Qaeda.
When the history of the effort is written - and the documents surrounding it are declassified - historians will doubtless seek to learn why the rebels lost ground for years, to Syrian government forces and their Russian and Iranian allies, and to extremists.
After the rebel's expulsion from the eastern half of the city of Aleppo last year, it became clear that they no longer posed a serious threat to Assad's rule.
But stopping the covert programme, which mainly helped rebels near the Turkish border in north-western Syrian and along the Jordanian border in the south, will not affect the fight against the militants of the Islamic State in Iraq and Syria (ISIS) in the east. A different programme there run by the Pentagon is supporting a Kurdish-Arab militia known as the Syrian Democratic Forces.