U.S. and Russian generals have held a first-ever face-to-face meeting this week in an effort to avoid accidental clashes as both sides fight to retake Islamic State (IS) territory in Syria, the Pentagon has said.
The Pentagon's disclosure on September 21 came after Russia had warned the United States that it will retaliate immediately if Syrian government forces come under fire from positions held by a U.S.-backed Kurdish-led militia in eastern Syria.
"They had a face-to-face discussion, laid down maps and graphics," in the first meeting of its kind, U.S. Army Colonel Ryan Dillon, a spokesman in Baghdad for the U.S.-led coalition fighting the IS extremist group, told a Pentagon briefing.
Dillon said Russian and U.S. ground forces in Syria had been coordinating by phone in the past month to avoid firing on each other.
U.S. Defense Secretary Jim Mattis later told reporters he was not concerned about an accidental clash occurring on the ground in Syria. "I am not worried. We continue to deal with the Russians in a collaborative way. We'll sort this out," he said.
News of the top brass meeting came after a week in which the Russian and U.S. militaries traded charges that their troops or allies were endangered or struck by the other side's forces, fueling worries about accidental clashes.
The Russian Defense Ministry on September 20 accused U.S. spies of sparking a militant offensive against Syrian government-held parts of northwest Syria to thwart the government's gains there.
The ministry said that during the incident on September 19, 29 Russian military policemen were surrounded by extremists and Russia had to rescue them in a special operation backed by air power, with three of the troops suffering injuries.
"According to our information, U.S. intelligence services initiated the offensive to halt the successful advance of government troops to the east of Deir al-Zor," Russian Colonel General Sergei Rudskoi was quoted as saying by Reuters.
Prior to that incident, the U.S.-led coalition said Russian military jets on September 16 struck fighters from the Syrian Democratic Forces (SDF), a Kurdish-led militia backed by Washington, in Deir al-Zor Province, injuring six of the fighters.
The Russian Defense Ministry denied the accusation.
In the latest incident on September 21, Russian Defense Ministry spokesman Major General Igor Konashenkov said that Syrian troops operating alongside Russian special forces near the city of Deir al-Zor were "twice targeted with massive fire from mortar launchers and rocket artillery" from positions held by the SDF.
Konashenkov said the SDF fighters had taken up positions on the east bank of the Euphrates River with U.S. Special Forces. He said a representative of the U.S. military command in Qatar was "notified in severe form that attempts to attack from districts where SDF fighters are located will be repelled."
Konashenkov added that "fire positions in these areas will be immediately suppressed with all available weapons."
Ahmed Abu Khawla, an SDF commander whose unit is leading the fight in Deir al-Zor Province, denied the Russian accusations of shelling and accused Moscow of seeking to obstruct the U.S.-backed advance, the Associated Press news agency reported.
The United States and Russia back separate military offensives in the Syrian war, both of which are advancing against IS militants in the east of the country near Iraq.
The government forces, backed by Russia and Iranian-allied militiamen, have gained control of most of the city of Deir al-Zor.
The SDF, supported by U.S.-led coalition air cover, said on September 20 that its campaign to capture the IS stronghold of Raqqa, north of Deir al-Zor, was in its final stages and that its fighters had seized 80 percent of the city.
Konashenkov claimed that Russian intelligence shows the coalition's operation in Raqqa had stopped and that SDF fighters redeployed from there to Deir al-Zor. He did not provide evidence.
He also said that a Syrian government offensive captured two villages on the west bank of the Euphrates overnight, taking about 16 square kilometers of land.
With reporting by AP, AFP, Interfax, and Reuters