The US State Department said it would back Libya's internationally recognised Tripoli government against efforts by Russia to exploit the ongoing conflict.
“The U.S. delegation... underscored support for Libya’s sovereignty and territorial integrity in the face of Russia’s attempts to exploit the conflict against the will of the Libyan people". This was the strongest American warning yet since the LNA's April offensive on Tripoli began and Russia began sending mercenaries to help Haftar's efforts.
New estimates place the number of Russian mercenaries directly involved in combat roles at over 1400 troops - including in infantry, artillery and air support roles. One Western official estimated that there were 25 air force troops, including pilots and support crew, while other sources said the pilots were flying Sukhoi-22 jets belonging to the LNA. Russia denies it had mercenaries in Libya.
US policy ha been unclear on Libya. While the State Department backs the UN recognised Tripoli government and called for a cease-fire, President Trump personally indicated support for General Haftar earlier this year. However, the launching of the US-Libya Security Dialogue with the GNA made clearer Washington's position.
According to a Libya expert at the Middle East Institute, this is more of a reaction to Russia's presence than it is support for the GNA.