Syria's Bashar Assad has vowed to retake territories held by the PKK-affiliated Syrian Democratic Forces (SDF), which is backed by the U.S., through force if diplomatic options failed.

In an interview with Russia's state-owned Russia Today TV yesterday, Assad said the government opened doors for negotiations with the SDF, adding that if diplomacy fails, they will use force to retake the areas. "The Americans should leave, somehow they're going to leave," he said.

The SDF is an umbrella group predominantly led by the PKK's Syrian affiliate People's Protection Units (YPG). It controls nearly 25 percent of entire Syria. The terrorist organization has been militarily supported by Washington - one of the several reasons behind the recent deterioration in the Turkish-U.S. relations.

Although the U.S. recognizes the PKK as a terrorist organization, it denies the group's connection with the YPG and the SDF despite all the proofs suggesting otherwise. In a show of support to the terrorist organization, U.S. troops are currently deployed in Syria's SDF-held areas.

Assad further emphasized that the U.S. invaded Iraq on a legal basis and Syria is no exception. He said people will not accept foreigners in the region anymore. The U.S.-led invasion of Iraq that toppled Saddam Hussein in 2003 was followed by a long-running insurgency and civil war, causing the death of hundreds of thousands of people.

In April, U.S. President Donald Trump said he wanted to pull out American troops from Syria. However, numerous U.S. officials to, including Defense Secretary Jim Mattis, objected to the idea.

Mattis said on April 30 that Washington and its allies would not want to withdraw troops out of Syria before diplomats established peace in the region.

With the backing of Russia and Iran, Assad regime recently recovered swathes of territories and now controls the majority of Syria. Yet, the regime forces still tracts at the borders with Iraq, Jordan and Turkey, three of the five neighborhood countries, which remain outside of his authority.

Syrian civil war erupted in 2011 when Assad regime reciprocated to protesters poured into streets to demand more rights and freedom with harsh treatment. The protests initially emerged following the Arab spring demonstrations resulted in the step down of strongmen in Egypt, Tunisia and Libya. The cruelty against protesters triggered a rebellion in significant parts of the country, turning into a brutal civil war before long. So far an estimated half a million people have been killed in the war. Around 6 million people have been displaced internally and another 5 million were driven abroad as refugees.

Erdoğan met with Putin's envoy to Syria

President Recep Tayyip Erdoğan received Assad's main backer Russian President Vladimir Putin's special envoy for Syria, Alexander Lavrentiev, yesterday, at the presidential complex in Ankara.

Lavrantiev is leading the Russian delegation in Astana talks, which was initiated by Turkey, Russia and Iran in January 2017 to establish a a cease-fire between the Syrian opposition and the Assad regime and deliver humanitarian aid to those in need.

Ankara objects presidency of Assad in Syria, which backed by Russia and Iran, and is advocating for a political transition period. However, this objection does not exempt the country from holding negotiations with Moscow and Tehran to find a permanent solution for the Syrian civil war.