Three U.S. service members of the NATO-led coalition forces were killed in an insurgent attack in the eastern province of Paktia on Sunday.

"Three International Security Assistance Force (ISAF) service members died following an enemies of Afghanistan attack in eastern Afghanistan today," ISAF announced in the statement it released to media on Sunday.

Although the statement did not offer any information about the nationalities of the slain soldiers, ISAF officials confirmed in a press conference on Monday that they were U.S. service members. U.S. officials reported separately to Reuters that the attack occurred in the eastern Paktia province.

The deaths mark the first NATO combat casualties this month, the last one occurring back in July. These deaths raise the number of foreign troops killed in action in Afghanistan this year to 114.

U.S. soldiers primarily comprise the NATO-led troops based in Paktia and other eastern provinces. Although the province was the sight of some of the most intense fighting in past years of the 12-year war in Afghanistan, as of late the U.S. troops there have seen very little combat. Their duties have mostly entailed training and other capacity building efforts for the Afghan security forces since the final stage of the security transition began.

Of the roughly 100,000 foreign troops in Afghanistan, around 68,000 are Americans.

Foreign troops in Afghanistan are scheduled to leave by the end of 2014 with the end of the NATO combat mission, after which time the Afghan security forces – currently numbering at around 300,000 men – will take over full security responsibilities. Nevertheless, according to NATO and Afghan officials, the Afghan security forces have assumed the bulk of leadership on operations throughout the country already.