The US State Department is warning American citizens against traveling to Turkey due to an increased threat of terrorist attacks.

WASHINGTON (Sputnik) – Turkey has recently came under intense criticism for allegedly purchasing oil from Daesh, that the terror group has been stealing from Syria and Iraq, as well as supplying Daesh with weapons.

"Terrorists have targeted popular tourist sites, US government buildings, police, and other local authorities throughout Turkey. The threat of kidnapping remains a concern, especially in the southeast, and incidents of indirect fire from Syria have impacted Turkey along the border," the State Department said in a Thursday travel warning.

The Russian Defense Ministry said on Thursday that there were "serious grounds" to suspect Turkey of preparing for a military incursion in Syria.

"US citizens should exercise caution when traveling throughout the country [Turkey]," the US State Department warned on Thursday.

According to head of the foreign affairs committee of the lower house of Russia's parliament (State Duma) Alexei Pushkov, the Syrian opposition could have exited the intra-Syrian peace talks in Geneva to wait for a shift in the balance of power with Turkey’s possible intervention in Syria.

"The possible cause of the Syrian opposition’s withdrawal from the negotiations is a reliance on a shift in the balance of power in the event of Turkey’s military intervention in Syria," Pushkov wrote on Twitter.

Daesh is one of the radical groups that government forces in Syria have been fighting against. It is outlawed in a range of countries, including Russia.