ANKARA, Turkey — Turkish Foreign Minister Mevlut Cavusoglu said Wednesday that Turkey will not refrain from military action to protect its borders from what he describes as threats posed by Syrian Kurdish fighters.

The minister's comments came a day after Turkey rejected U.S. national security adviser John Bolton's demands for assurances that Ankara would protect U.S.-allies Kurdish fighters in northeastern Syria before American troops pull out from the region.

Turkey's rebuff amplified a rift between Ankara and Washington and raised new questions about how the United States would protect fighters who are U.S. allies in the war against the Islamic State group.

Turkey regards the Kurdish fighters as terrorists linked to Turkish insurgency.

Cavusoglu told Turkey's parliamentary foreign affairs committee the U.S. was "struggling to withdraw" from Syria because it was too far engaged with the militia group.

In northern Syria, Russian military police and the al-Bab Military Council group began joint patrols in an area close to the front lines with Turkey-backed opposition fighters, according to the Kurdish Hawar news agency and a Kurdish official.

Al-Bab Military Council is allied with the Kurdish-led Syrian Democratic Forces that have been fighting the Islamic State group with the help of the U.S.-led coalition.

Sharfan Darwish of the Kurdish-led Manbij Military Council also confirmed the joint patrols near the Kurdish-held town of Manbij.

Wednesday's patrols came a day after Russian military police started patrolling the surroundings of Manbij.

A representative of the military police told reporters Tuesday that Russia's mission is to ensure safety in the Manbij area, and monitor moves of militant groups.

The area near Manbij was previously occupied by U.S.-backed Kurdish-led forces, who were forced to appeal to Syria and Russia amid fears of a Turkish attack.

Russia's move came after U.S. President Donald Trump in December unexpectedly announced he would pull out 2,000 U.S. troops leaving strategic areas near Turkey's border up for grabs.