Washington (CNN)The US military has again accused Russia of sending weapons, including anti-aircraft missiles, to Libya and sending Russian mercenaries to operate on the front lines of the conflict there.

“It is assessed that the Russian Federation continues to violate UN Security Council Resolution UNSCR 1970 by actively providing military equipment and fighters to the front lines of the conflict in Libya,” US Africa Command, which oversees US military operations on the continent, said in a statement on Friday.

US officials have long accused Moscow of using the Russian mercenary outfit known as the Wagner Group to fight in the Libyan civil war as part of an effort to extend Russia’s influence in the oil-rich North African country while also establishing a presence on NATO’s southern flank.

“Russia uses Wagner Group as a proxy in Libya to establish a long-term presence on the Mediterranean Sea,” Africa Command said.

“They continue to look to attempt to gain a foothold in Libya,” Brig. Gen. Gregory Hadfield, the command’s deputy director of intelligence, said in the statement.

Russia and Turkey involved in Libya’s civil war

US officials have described both sides of the Libyan Civil War as increasingly relying on foreign support.

The Tripoli-based and UN-recognized Government of National Accord has received support from Turkey, including drone strikes and Turkish funded Syrian mercenaries, while its adversary, the Libyan National Army commanded by Gen. Khalifa Haftar, has received the backing of Russian mercenaries and some Arab counties, including Egypt.

Africa Command has previously released evidence of what it says is Russia’s presence in Libya, accusing Moscow of sending warplanes to bolster Haftar’s forces and of deploying mines in an effort to slow the advance of the Government of National Accord, which has pushed Haftar’s forces back toward their eastern strongholds.

Amid an increase in fighting, President Donald Trump has spoken with several leaders in recent days about the situation in the country, including French President Emmanuel Macron and Egyptian President Abdel Fattah El-Sisi, who has threatened to send troops into Libya should forces aligned with the Government of National Accord continue to advance.

Trump also spoke with Russian President Vladimir Putin Thursday, but the topic of Libya was not mentioned in the White House’s or Kremlin’s official readouts of the call.

Africa Command also released imagery Friday purporting to show Russian military equipment being operated by Wagner Group mercenaries, including Russian armored vehicles positioned near where the heaviest fighting between Tripoli and Haftar’s forces is taking place.

“U.S. Africa Command has mounting evidence that Russia, through the Wagner Group, continues to position military equipment in Libya capable of conducting kinetic operations there. Overhead imagery shows Wagner forces and equipment on the front lines of the Libyan conflict in Sirte,” the statement said.

“The type and volume of equipment demonstrates an intent toward sustained offensive combat action capabilities, not humanitarian relief, and indicates the Russian Ministry of Defense is supporting these operations,” Maj. Gen. Bradford Gering, the Africa Command director of operations, said in a statement.

Pentagon releases new imagery showing alleged Russian involvement

The accusation comes amid heightened tensions between Washington and Moscow over a range of issues. In recent days, the US has accused Russia of a wide range of activities, including testing a space-based anti satellite weapon, cyberattacks on organizations involved in coronavirus vaccine development and human rights abuses.

The imagery released by Africa Command purports to show Russian military cargo aircraft, including IL-76s, supplying Wagner fighters as well as Russian air defense equipment, including SA-22 missile systems at a Libyan air base under the control of the forces of Haftar.

Africa Command also provided an image showing that they said was “Wagner utility trucks and Russian mine-resistant, ambush protected armored vehicles” operating near Sirte, Libya close to the front lines of the conflict between Haftar’s forces and the forces of the Libyan Government of National Accord which is being backed by the Turkish military and Turkish funded Syrian mercenaries.

A Department of Defense report released earlier this month said that there are as many as 2,500 Russian mercenaries operating in Libya.

The report also said that 3,500 to 3,800 Syrian fighters, paid by the Turkish government and given a promise of Turkish citizenship, have joined the ranks of the Government of National Accord.

Turkish drone strikes have also bolstered the side of the Tripoli based government of National Accord, with the UK Defence Secretary Ben Wallace saying earlier this month that Turkish Bayraktar TB-2 drones in Libya “have conducted intelligence, surveillance and reconnaissance and targeting operations against frontlines, supply lines and logistics bases” since 2019.

“In July last year, they struck the Libyan National Army controlled Jufrah airfield destroying several command and control nodes as well as two transport aircraft,” Wallace said.

The presence of Russian and Turkish forces in such close proximity with the prospect of Egyptian troops entering the conflict has led some US officials to become concerned about a major escalation in the conflict.