Suicide bombers targeted a joint U.S.-Afghan military base in eastern Afghanistan on Sunday, killing at least 5, according to reports.
The attack, which officials described as "complex" took the lives of three Afghan soldiers and two civilians at Forward Operating Base Fenty, NATO command said.
This latest attack comes as Washington and Kabul work to hand over responsibility for security to Afghan forces in 2014, as U.S. and NATO combat forces leave the country.
But continued violence has left some top administration officials considering options for extending the U.S. presence in Afghanistan.
The New York Times and The Wall Street Journal reported last week that the White House was weighing proposals for post-war troop numbers that could keep as many as 10,000 U.S. servicemembers in Afghanistan after 2014.
Those plans could face strong opposition from congressional Democrats who have pushed for maintaining the current drawdown timetable.
Many Republicans, though, are concerned drawing down all U.S. forces from the country could leave Afghanistan susceptible to increased instability, citing the continuing violence in Iraq as an example.
Reports said the Sunday attack on the U.S.-Afghan base began after 5 a.m. when insurgent forces detonated a car bomb near the entrance to the installation.
The initial blast was followed by two other car bombs at the front gate and along the perimeter of the facility.
"Afghan National Army and International Security Assistance Force soldiers repelled the attack and prevented any insurgent fighters from entering the perimeter, causing numerous insurgent casualties in the process," said a statement from an Afghan Police spokesperson.
Reports said the Taliban had claimed responsibility for the attack.