The Pentagon on Monday denied a claim by Russia's defense ministry that the two nations coordinated on an airstrike targeting an Islamic State target in Syria.
The ministry said Moscow received coordinates for the strike on a US-Russian communications channel and participated in the strike with US-led coalition forces.
The US military, now being run by Secretary James Mattis, denied the claim.
"The Department of Defense is not coordinating airstrikes with the Russian military in Syria," Pentagon spokesman spokesman Eric Pahon said.
The Pentagon added that it was not aware of any coalition member aiding Russia, either.
Both the United States and Russia have been engaged in combat with militants in Syria for many months, but have largely been on opposite sides of the conflict. Russia is a key Syrian ally in the country's ongoing civil war, while the United States has supported a coalition of fighters in behalf of rebels.
President Donald Trump's administration has been open about its desire to improve relations with Russia. Spokesman Sean Spicer said Monday that the president is willing to "work with any country that shares our interest in defeating [the Islamic State]" -- including Russia.
The United States and Russia do have a communication hotline, though it exists primarily for safety reasons.
"[The Pentagon] maintains a channel of communication with the Russian military focused solely on ensuring the safety of aircrews and de-confliction of coalition and Russian operations in Syria," Pahon said.
