KABUL: NATO forces say that two U.S. service members were killed in a bomb strike in southern Afghanistan.

The international military coalition said the attack happened Tuesday but did not provide further information. The military typically holds back details on attacks until families have been informed.

Volatile southern Afghanistan has seen increasing violence over the past 12 months with an increase in NATO forces, particularly deaths and injuries from planted bombs targeting vehicles of international forces or soldiers on foot patrols.

President Barack Obama has ordered an additional 30,000 U.S. troops to Afghanistan to turn back the resurgent Taliban. In all, three U.S. service members have died this month. Thirty American troops died in January, compared with 14 in the same month of 2009.