benghazi libya car bomb checkpoint kill four troop libyan commander khalifa haftar force thursday attack claim islamic state officials security source say haftar libyan national army one powerful arm brigade libya rival factions military backers compete control since fall former leader muammar gaddafi 2011 uprise car bomb explosion target checkpoint nawfiliya town result two kill sirte security directorate wound lna spokesman ahmad mesmari tell reuters two security source late say two soldier die islamic state claim attack accord militant group amaq news agency haftar force fight islamist militants foes eastern benghazi besiege city derna try oust militants thursday attack nawfiliya 80 km 50 miles ras lanuf part libya oil crescent one opec country major oil export terminals libyan officials concern islamic state may try regroup defeat nearby sirte city last year car bomb kill four libyan troop checkpoint security source