The three countries, which are part of the Astana peace process regarding Syria, released a joint statement on Tuesday that “expressed their opposition to the illegal seizure and transfer of Syria’s oil revenues”.

They also “condemned the illegal oil deal between a U.S. licensed company and the illegitimate entity as part of its separatist agenda”.

The “illegitimate entity” was a reference to the U.S.-backed, Kurdish-led Syrian Democratic Forces (SDF), which Turkey regards as a terrorist group due to its affiliation with the outlawed Kurdistan Workers’ Party (PKK).

The U.S. has worked with the SDF since 2015 as its partner in the fighter against the Islamic State (ISIS).

While U.S. President Donald Trump’s administration wants to secure access to oil in Syria and the Pentagon wants to ensure ISIS is not able to re-group.

Turkey, Iran and Russia are keen to end the influence of the U.S. in the country.

Frantzman said Iran is pressuring the United States along the Euphrates by seeking to use tribes to undermine the SDF, while Turkey does the same in Tel Abyad by cutting off water to SDF-controlled areas and Russia uses patrols to harass U.S. forces.

“Slamming the U.S. oil deal is just the latest way that Iran, Turkey and Russia seek to work together,” Frantzman said.

Reporter’s code: 50101