Western observers consider Russia's role in Egypt, Libya and Syria as a challenge to NATO, which tried to overthrow leaders in all three Mediterranean states.
The Libyan city is ISIS's most important stronghold in the country.
Amid the celebrations in Derna, schools are reopening and people are returning to work.
But other rebels say they won't be so welcoming to the new regime.
Witnesses say some of the casualties were civilians.
The group of commandos were ordered to leave immediately after arriving at Libyan air base.
The internationally recognized parliament in Tobruk and the rival parliament in Tripoli meet to discuss unity plan.
Representatives of the Tobruk and Tripoli parliaments have proposed an initial deal to form a national government.
No reported casualties in latest of embassy attacks in Libya, following assaults on South Korean and Moroccan embassies.
Explosion damages Moroccan embassy in Tripoli the day after gunmen kill two in attack on South Korean mission.
Ahead of sanctions review in June, minister says Libya must be considered as equal a threat to Ukraine.
Fighting between IS and Libya Dawn has forced civilians to flee to Misrata.
As jihadis use cultural vandalism as a weapon of war, fears are increasing for the country's Greco-Roman heritage.