Senior adviser to Iran's Supreme Leader, Ali Akbar Velayati, quoted by the Tasnim News Agency, said following talks with Syrian Foreign Minister Walid al-Muallem on 6 February that whether the US wills that or not, it "should leave Syria". Velayati further stated that Damascus currently controls 90% of the land and will soon liberate the rest.
Iranian President Hassan Rouhani, who also participated in the talks, added that the "stability and complete security of Syria" and the return of its people to normalcy is one of Iran's key foreign policy goals.
Muallem thanked Iran for its help and said that as long as the two states stay together, they will achieve "victory against terrorism [and] colonialism".
Washington announced the pull-out of its troops from Syria in December 2018 promising to send around 3,000 soldiers back home in the coming months. However, some of the country's allies, as well as American politicians, fear that the military withdrawal might lead to a resurgence of Daesh* and attacks against Washington's Kurdish allies by Turkey.
In addition, Turkish newspapers reported that the US military contingent has actually increased since the announcement of the pull-out.
*Daesh (also known as ISIS/ISIL/IS) is a terrorist organisation banned in Russia