On December 19, the White House said the estimated 2,000 US troops are being withdrawn from Syria since the extremist organization, the Islamic State (IS) in Syria had been "defeated".

The US President Donald Trump subsequently issued a message on Twitter saying that the United States "has already defeated" the IS in Syria, the "only reason" for being there during his presidency. The evolution of the situation in Syria signifies that the United States has in fact abandoned the goal of overthrowing the regime of Syrian President Basharal- Assad.

The US-led international coalition forces began operations against the Islamic State group in Syria since 2014. After the Russia's direct military involvement in the situation in Syria since 2015, the Syrian opposition groups supported by the United States collapsed, and the President Bashar al-Assad's regime gradually stabilized.

Under such circumstances, it is not surprising the decision to withdraw the US troops from Syria is made since the Trump administration based on its principle of "America first" is unwilling to assume excessive security responsibilities for its allies.

"Money" is an important factor to force the US withdrawal from Syria this time. The US President Trump has always been dissatisfied with the large-scale US military presence overseas, and believed that this huge cost has not brought substantial benefits to the United States.

On April 3 this year, he said that in the past decade, the US military operations in the Middle East have cost a lot while achieved "nothing" and hoped that the United States can withdraw its troops from Syria.

Surely this is not a simple problem. What has prompted the Trump administration to make such a decision would undoubtedly stand on a huge temptation of benefits, that is, the withdrawal would improve the US relations with its traditional ally, Turkey.

For many years, Turkey has always been anxious about the domestic disputes due to the expansion of Kurdish forces in northern Syria. At the beginning of this year, despite the pressure of international public opinion, Turkey launched a cross-border military action dubbed "Operation Olive Branch" to attack the Kurdish enclave in northern Syria.

The United States has always supported the Kurdish armed forces in Syria during the Syrian war. Most of the US troops in Syria are stationed in the north of Syria in the name of helping to train the Kurdish and Arab armed forces to fight against the IS. The US backup has also become an important incentive for US-Turkey tension in recent years.

Obviously, the withdrawal of the United States troops at this time is undoubtedly an "abandonment" of and "betrayal" against the Kurds. In view of the ever heating-upTurkey-Russia relationship in recent years, the US move might also attempt to woo Turkey and to prevent Turkey’s ever-closer ties with Russia.

On December 12, Turkish President Recep Tayyip Erdogan said that Turkey will launch a military operation in the east of the Syrian Euphrates River "within a few days". The Pentagon issued a statement stating that it was "unacceptable."

The US-Turkey leaders talked over the telephone on the Syrian issue on December 14, and a few days later Trump made the decision to withdrawal. The Turkish side welcomed the decision and postponed its launch of the military operation.

Even if the US troops are withdrawn from Syria, the US military will remain fairly large in the Middle East. White House spokesperson Sarah Sanders said on December 19 that defeating the extremist organization IS does not mean the end of the international coalition forces, nor does it mean the end of the crackdown.

The United States and its allies will continue to act if needed to defend the US interests, and will continue to work together to stop terrorists from acquiring land, funds and support, and to prevent them from entering the United States or its allies.

There may be many reasons for making such a decision, and the consequences will also be complex. What is certain is that the withdrawal of the United States troops will add new variables to the delicate situation in Syria.

Where do the Syrian Kurds go after losing the US’s protection? Can Turkey advance triumphantly? Will the defeated IS which has not been vanquished rise again? These questions remain unanswered.

Disclaimer: The author is Feng Ying . The article was published on the PLA Daily on Dec. 22. It is translated from Chinese into English and edited by China Military online.