Since the outbreak of Syria's brutal civil war, the United States has stated several objectives -- destroying Islamic State extremists, easing from power President Bashar al-Assad and limiting Iran's influence.
In just one decision, President Donald Trump may have undone all three.
The mercurial leader pulled US troops out of northern Syria in the face of a Turkish invasion against Kurdish forces, who had led the campaign to crush the Islamic State group and with US protection had enjoyed effective autonomy.
The Kurds have reached out to Assad's regime -- allied with Iran and Russia -- to redeploy for the first time in years to northern Syria to face Turkey, which is trying to eliminate a force it links to Kurdish separatists at home.
Trump, who is skeptical of US military engagements overseas, already declared a withdrawal from Syria in December before backtracking but appeared to be convinced in an October 6 telephone call with Turkish President Recep Tayyip Erdogan.
"We are now facing a situation that one could have foreseen in December, but it is being done in a way that it's having all of the worst consequences that one could have feared," said Robert Malley, president of the International Crisis Group, which studies conflict resolution.
"It raises even more questions about reliability, so many of America's allies in the region are going to wonder what will it take for President Trump to turn around and no longer consider us partners or allies," he said.
- Damage 'for years to come' -
Elizabeth Dent, a scholar at the Middle East Institute who served as the special assistant to the US envoy in charge of defeating the Islamic State group, saw risks of a resurgence of the extremists and said that the United States could have prepared ahead of time.
"Had the US actually planned a more formal withdrawal we could have ensured that detainees were properly secured prior to pulling back forces," she said.
She doubted that the pullout in itself would have long-term consequences for the United States in the Middle East, saying that both Russia and Iran have historically had deeper ties in Syria while Washington is more active elsewhere.
"But the way the decision was made -- abruptly, with no planning, an optic of the US being forcibly removed or conceding to Turkish demands, and an abandonment of our partner force -- will certainly have an impact on US credibility and reliability for years to come," she said.
She said it was only a matter of time before Assad, who has triumphed militarily in much of the country, reached a deal with the Kurdish-led Syrian Democratic Forces.
Former president Barack Obama had called for Assad's ouster but the United States more recently has depersonalized its position, instead calling for an inclusive political process to end one of the most devastating wars in recent memory, which has killed more than 370,000 people and displaced millions.
The Obama administration allied with the Kurds to fight the Islamic State group after deciding that Syria's rebels were not moderate or credible enough to support.
- US always 'confused' -
"America has always been confused about what it's doing in Syria. It inflated the expectations of the Kurds well beyond what it could deliver," said Joshua Landis, an expert on Syria at the University of Oklahoma.
"The United States was never going to be in Syria for the long haul and help establish a quasi-independent state with the Kurds. That was a pipe-dream," he said, pointing to wide opposition in the region to Kurdish aspirations.
Landis played down the chances that the Islamic State group will benefit, saying that US military action had already decimated the extremists and that Syrian government authority was the long-term solution -- "not having American police on the ground."
But he agreed that the pullout, along with Trump's calls for a lighter footprint in the Middle East, would boost both Iran and Russian President Vladimir Putin.
Trump since taking office has vowed to curb Iran's influence in the region, pulling from a nuclear accord and imposing sweeping sanctions, but has also held off from military action as tensions soar.
The Pentagon ordered reinforcements Friday to Saudi Arabia after an attack on its oil plants which Washington blamed on Iran. But on Monday, the longstanding US ally was rolling out the red carpet for a high-profile visit by Putin.
"The stock of President Trump has plummeted in the Middle East and that of President Putin is skyrocketing today because nobody trusts President Trump -- they feel that he is going to yank America out of the Middle East willy-nilly and they're going to be left on their own," Landis said.