The White House on Tuesday raised concerns about escalating tensions in Libya, citing "foreign military involvement" in the nation's civil war.

National security adviser Robert O'Brien said the U.S. "is deeply troubled" by the conflict in Libya and warned against unnamed foreign actors getting involved there. The statement did not name any particular nation despite the Pentagon previously calling out Russian mercenaries in the region.

"We strongly oppose foreign military involvement, including the use of mercenaries and private military contractors, by all sides," O'Brien said in a statement issued by the White House. "The ongoing efforts of foreign powers to exploit the conflict – for example, by establishing an enduring military presence or exerting control over resources that belong to the Libyan people – pose grave threats to regional stability and global commerce." 

"Furthermore, these efforts undermine the collective security interests of the United States and our allies and partners in the Mediterranean region," he added. "Escalation will only deepen and prolong the conflict."

O'Brien, who returned to work at the White House on Tuesday after recovering from COVID-19, called the U.S. an "active, but neutral, actor" in the conflict. He called for all actors in the region to allow for a cease-fire to take place.

O'Brien noted that President Trump has in recent weeks spoken with multiple world leaders about the situation in Libya. Trump discussed Libya with the presidents of France and Egypt this summer, but it's unclear if he talked about the Libyan conflict during a July call with Russian President Vladimir Putin.

Libya has been mired in a civil war dating back to the overthrow of Muammar Gaddafi in 2011. The Middle Eastern nation has since become the site of a proxy war, with rival factions seeking to assert control.

Turkey supports the United Nations-backed government of Prime Minister Fayez al-Sarraj, while Egypt, Russia and the United Arab Emirates are supportive of military commander Khalifa Haftar.

The Pentagon last month accused Russian mercenaries in Libya of planting landmines and improvised explosive devices (IEDs) in and around Tripoli, the war-torn country’s capital.

Russia, which has denied involvement in the Libyan civil war, also transferred aircraft to the North African nation in May. Africom said that at least 14 MiG-29s — with their Russian markings painted over — were flown from Russia into Syria and then Libya, a violation of the United Nations arms embargo.