While Trump wants to pull out of the 900 troops there saying Syria is of no consequence to the US and we should stay out, Biden said boots on the ground to remain as his administration was monitoring the developments. US troops are there for varied reasons to protect US national security and ward off any threats from the HTS, an Al Qaeda splinter group and the ISIS, both of which are terrorist organisations in the eyes of the US government.
The HTS of al Julani which took over Syria is a rebel force fighting the oppressive regime of Assad and it was encouraged by neighbouring Türkiye, a sworn enemy of Assad, to launch the offensive and take out Assad’s army by surprise. Reports indicate that Assad’s forces offered little resistance to the rebels marching into Damascus and taking over the capital.
Assad did not get the expected help from Russia and Iran, who had been backing his regime, were distracted by the swift movement of the rebels and could not swoop down as they were engaged in their own wars in Ukraine and the Middle east. Rebels led by the Hayat Tahrir al-Sham terrorist group rapidly worked through the country, seizing Aleppo, Hama, and Homs, before finally entering the capital Damascus on Sunday. Shortly thereafter, they declared that Assad had fled.
Before the Damascus developments, the United States had expressed a righteous indignation toward the renewed hostilities, but the country has stayed on the sidelines — issuing limp statements urging a democratic election for the future of the nation and the dismantling of its infamous chemical weapons facilities., the Washington Examiner said in a report.
It would appear the U.S. government doesn’t have much of a stomach for involvement in Syria at this point, a distaste that is residual from the botched weapons distributions, influence networking, and empty threats attached to the legacy of President Barack Obama‘s administration, and his failure to get a proper handle on the situation in the first place. 
The uprising in Syria is being pinned on the alleged failure of Barack Obama on his foreign policy in that region.
Dipping a toe, but afraid to swim
The White House began calling for Assad to step down in 2011 following a string of demonstrations against his regime and harsh authoritarian crackdowns in response.
In August 2013, rebel-controlled areas in Ghouta near Damascus were struck with a Sarin gas attack — a vicious nerve agent that can kill victims within minutes through excruciating suffocation. The world already knew that Assad had those capabilities — the Syrian government acknowledged its possession of chemical weapons in 2012, threatening their use in the event of an international conflict.
Approximately 1,400 people were killed in the Ghouta attack, while a further 3,600 were injured. It was a breach of countless international treaties and confirmed the regime’s willingness to use weapons of mass destruction to suppress its internal opponents.
Assad, his regime, and some Kurdish figures denied the president’s involvement — instead, blaming rebel forces and their international backers as a way to provoke a foreign intervention. The war crime put the Obama administration in a difficult position.
Just a year earlier, the president had issued his infamous “red line” ultimatum that threatened air strikes and direct military action against Assad if chemical weapons were deployed.
“We have been noticeably clear to the Assad regime, but also to other players on the ground, that a red line for us is we start seeing a whole bunch of chemical weapons moving around or being utilized. That would change my calculus,” Obama said in 2012, a year before the sarin attack in Ghouta. “That would change my equation.”
But when that “red line” was crossed with lethal nerve agents, the White House flinched. Obama expressed hesitancy to his advisers about following through with the threat.
The thinking went something like this — a comprehensive attack sufficient to topple Assad would leave a power vacuum to be filled by an even more radical, inhumane dictatorship. Alternatively, a half-hearted or restrained attack would make the U.S. look like an impotent geopolitical actor, a pseudo-superpower unwilling to make good on its own threats, the Examiner said.
On Sep. 6, then-Senate majority leader Harry Reid introduced a resolution that would authorize military force against Syria. The U.S. government was being dragged into a hot conflict it both instigated and desperately wanted to avoid. In his appeal for military action to Congress, Obama promised no U.S. boots on the ground. 
The critical pressure found a release valve when on Sept. 9 State Secretary John Kerry spoke with a reporter about the possibility of avoiding military action. Kerry asserted that if Syria simply dismantled its chemical weapons program, air strikes would not be necessary.
Russia offers a fig leaf.
The White House’s political salvation came from an unlikely source — Russian President Vladimir Putin and the Kremlin. Within an hour and a half of stating that Syria could avoid an American airstrike if the government gave up its nuclear weapons, the Russian foreign minister contacted Kerry.
“I got a phone call from Sergey Lavrov of Russia suggesting that was a really good idea, why don’t we work on whether or not we could do that?” Kerry recalled at a 2017 press conference. “And President Obama and President Putin had actually talked about it a few weeks earlier in St. Petersburg, and I’d already talked to Lavrov – I’d actually talked to Prime Minister Netanyahu about it, who thought it was a good idea.”
A deal was reached in mid-September and the Russians agreed to aid the Syrian government in destroying the chemical weapons. Authority to oversee the process was vested in the Organization for the Prohibition of Chemical Weapons (OPCW).
This arrangement — which ostensibly completed the destruction of all Syrian-controlled chemical weapons — was a farce. The Syrian government formally declared only a fraction of its chemical weapons infrastructure. The Assad regime had no intention of destroying its most effective weapons against the rebels seeking to overthrow them.
A problem that will not go away.
The city of Khan Sheikhoun was struck with a sarin gas attack on Apr. 4, 2017. It killed approximately 90 people, including 30 children. The Syrian military once again denied involvement, claiming that it “has never used [chemical weapons], anytime, anywhere, and will not do so in the future.”
Assad claimed the reports of nerve agents were fabricated, accusing the U.S. of working “hand-in-glove with the terrorists.” “They fabricated the whole story in order to have a pretext for the attack,” he said, questioning whether dead children from Khan Sheikhoun shown on video were real or actors.
Russia ran cover for the Syrian government, speculating that a Syrian air force strike had struck “workshops which produced chemical warfare munitions” for rebel forces.
Despite all the posturing and agreements formalized at the highest levels of international diplomacy, Syria’s condition did not improve. No long-term stability was found. Atrocities did not end. Allies turned to enemies, enemies became embittered, and the U.S. gained nothing but a headache that continues to the current day.
Even worse, clandestine operations to undercut the Syrian government — kept secret from the public for years — had gone off the rails and exacerbated the problem.
The U.S. government began covertly providing arms to anti-Assad rebel forces as early as 2013. The operations were a joint effort with allies in the region such as Jordan and Saudi Arabia, aimed at keeping the pressure on the Syrian president.
CIA-coordinated programs such as “Timber Sycamore” aimed to put weapons furnished by the U.S. government into the hands of opposition militia that would be fighting for a democratic future in Syria. Many of those weapons were stolen by intermediaries and sold on the black market to terrorist groups. Others made it to their intended recipients, who later jumped to more radical, undemocratic militia.
Among those militias that benefited from these American-trained turncoats and their equipment was the al Nusra Front, an Al Qaeda affiliate in Syria that eventually became HTS — the rebels currently marching towards Damascus. Amid the chaos, the Islamic State terrorist group seized large swaths of territory in Syria and built momentum for their jihadist movement.
Obama mocked the group in a 2014 interview, brushing them off as the “JV team” of Islamic terrorism compared to more dangerous and well-resourced militia. In just a few years, ISIS would establish a caliphate over one-third of Syria and almost half of Iraq, becoming one of the most belligerent and dangerous terrorist organizations in the world.
Insanity is doing the same thing over and over and expecting a different outcome. The United States now watches the violence and political upheaval taking place in Syria with exasperation and frustration. Over a decade of passive involvement in one of the world’s most volatile civil wars has produced nothing to benefit the United States, Syrian civilians, or greater humanitarian interests.
Bill Roggio, a senior fellow at the Foundation for Défense of Democracies and expert, told the Washington Examiner that the ultimate failure of Obama-era foreign policy in Syria was the lack of a clear mission. “Everybody wanted to do something but didn’t know who to do it with — and really there were no good options do it with anyone,” Roggio told the Examiner. “Yet we still tried, did not try hard enough, and did just enough to fail and to look inept. What kind of legacy is that?”
The United States released a joint statement with the United Kingdom, France, and Germany on Dec. 1 as rebel forces took Aleppo. The countries urged “de-escalation by all parties and the protection of civilians.” The statement also pushed for all parties to abide by United Nations Security Council Resolution 2254, a toothless agreement that would demand Assad cede power to facilitate a free and fair democratic election.
Assad’s past use of sarin — and his failure to abide by agreements to disarm such chemical weapons — has also been trotted back out by U.S. diplomats. But this time, no threats are being made other than the disapproval of international bodies.
“At this moment when we see the regime and its backers ramping up attacks on civilians in Aleppo and Idlib, our message is simple: the eyes of the international community are on you and will remain on you until justice and accountability are reached,” said U.S. Ambassador Robert Wood.
President-elect Donald Trump seems dead set to put Syria in the rearview mirror during his second term, referring to the country as the place “where former President Obama refused to honour his commitment of protecting the RED LINE IN THE SAND, and all hell broke out, with Russia stepping in.” 
“There was never much of a benefit in Syria for Russia, other than to make Obama look really stupid,” Trump continued. “In any event, Syria is a mess, but is not our friend, and the United States should have nothing to do with it. this is not our fight. let it play out. do not get involved!”
Source; The Washington Examiner – An analysis of current developments in Syria.
