U.S. and Afghan troops abandoned the isolated base in eastern Afghanistan where militants killed nine American soldiers this week, NATO officials said Wednesday. This was yet another evidence of the struggle in confronting foreign and Afghan security forces spread along the mountainous border between Afghanistan and Pakistan.

According to NATO and Afghan officials, Taliban fighters swarmed the area as the troops backed out from the improvised outpost near the secluded village of Wanat.

Beside the nine U.S. soldiers killed, 15 American and at least four Afghan troops were injured after rebels penetrated the outer area of the station. The assault was the deadliest in Afghanistan since a helicopter was shot down killing 16 American GI’s in 2005.

Officials said that the combat outpost in Wanat, located in Konar province, had been operational for only two or three days before hundred of Taliban belligerents assault it with rocket-propelled grenades, mortar shells and gunfire Sunday.

Somewhere else in the frontier region, NATO launched artillery and helicopter assaults hitting targets inside Pakistan after the ISAF received insurgent rocket fire from across the border, according to officials.

"The troops identified a (compound) as the point of origin of the attacks and responded in self-defence with a combination of fire from attack helicopters and artillery into Pakistan," the alliance said in a statement. Nine Afghan soldiers were injured by the rocket attacks and NATO’s ISAF responded right away.

Afghan and NATO officials blame the de-facto truces between the Pakistani military and the combatants in its lawless tribal belt for the high tension dominating the border as has bee recorded a sharp increase in attacks in eastern Afghanistan coming from inside Pakistan.