BEIRUT — The main Syrian Kurdish-led militia warned on Thursday that threats by Turkey’s president to launch a new military operation against U.S.-backed Kurdish fighters in Syria will negatively impact their fight against the Islamic State group.

Nuri Mehmud, spokesman of the Syrian Democratic Forces, also said that Turkish President Recep Tayyip Erdogan’s statement from the day before about a new operation “within a few days” is tantamount to a declaration of war.

Mehmud spoke as SDF fighters pushed deeper in the Hajin area, the last ISIS stronghold in Syria. He expressed hopes that the presence of troops from the U.S.-led coalition in northern and eastern Syria would deter Turkey from an offensive similar to the one Ankara launched earlier this year in the northern Syrian enclave of Afrin.

In recent months, Turkey has shelled Kurdish positions across the border in Syria, east of the Euphrates River, and has threatened to drive out the Syrian Kurdish militia known as the People’s Protection Units, or YPG.

The YPG is the main component of the SDF that rolled back ISIS from wide parts of Syria with the help of the U.S.-led coalition. Ankara views YPG fighters as terrorists because of their links to the Kurdish insurgency inside Turkey. U.S. troops are deployed with the Kurdish fighters in northeastern Syria, in part to prevent clashes with Turkey.

A military vehicle is transported as part of a convoy on the outskirts of the city of Kilis, southeastern Turkey, close to the border with Syria, Thursday, Dec. 13, 2018. Turkey's state-run news agency says a convoy of military vehicles arrived at the border with Syria a day after President Recep Tayyip Erdogan said Turkey would stage a new military operation against U.S.-backed Kurdish fighters in northern Syria. (Ismet Bicen/IHA via AP)
A military vehicle is transported as part of a convoy on the outskirts of the city of Kilis, southeastern Turkey, close to the border with Syria, Thursday, Dec. 13, 2018. Turkey's state-run news agency says a convoy of military vehicles arrived at the border with Syria a day after President Recep Tayyip Erdogan said Turkey would stage a new military operation against U.S.-backed Kurdish fighters in northern Syria. (Ismet Bicen/IHA via AP)

Turkey's state-run news agency reported that a convoy of Turkish military vehicles arrived at the border with Syria on Thursday. Anadolu Agency said the convoy, including armored personnel carriers, was deployed to the province of Hatay as reinforcents. The agency reported similar troop movement earlier this week.

Meanwhile, SDF fighters pushed deeper into the Syrian town of Hajin, taking its main market amid intense fighting with the extremists in their last holdout on Thursday.

The Kurdish-led Syrian fighters have been fighting to take Hajin and nearby villages in Syria’s eastern province of Deir el-Zour since Sept. 10. Over the past weeks, the offensive intensified with the arrival of reinforcements from northern Syria.

The Britain-based Syrian Observatory for Human Rights said ISIS defenses “collapsed” in Hajin as the town’s main market was captured. The Observatory said SDF fighters were also able to evacuate some 600 civilians, many of them women and children, out of ISIS-held areas.

Europe-based Omar Abu Layla, of the activist-run DeirEzzor 24 monitoring group, confirmed the market was taken as well as the main mosque in Hajin.

“The end of the (ISIS) organization in Hajin is very near,” he said.

Also Thursday, UNICEF said two babies died in the refugee settlement of Rukban on the Syrian border with Jordan, where tens of thousands of people have been living amid shortage of food and medicine.

Last month, the U.N. and the Syrian Arab Red Crescent organized a desperately needed aid delivery to Rukban, the first since January.

Associated Press writer Suzan Fraser in Ankara, Turkey, contributed to this report.