The US says attacks on the border with Pakistan have increased
Attacks by Taleban insurgents in eastern Afghanistan have increased by 40% compared with the same period last year, the US regional commander says.
Maj Gen Jeffrey Schloesser said insurgents were choosing targets to disrupt economic development.
His remarks came on the day that a Nato soldier was killed when a patrol hit a mine in Nangarhar province.
Separately, 14 insurgents were killed by Nato air strikes after a gun battle with Afghan police in Paktia province.
Gen Schloesser said attacks on the border with Pakistan accounted for 12% of the total insurgent attacks in eastern Afghanistan.
Forty uniformed and civilian members of the coalition forces in the region have been killed since the start of April.
He blamed "a syndicate" of insurgents, including members of the Taleban and al-Qaeda, and people from both Afghanistan and Pakistan for the attacks.
"The enemy is taking refuge and operating with some freedom of movement in the border region," he said to reporters in Washington over a video-link from Afghanistan.
"The enemies are aggressively burning schools, killing teachers and students."
"Overall, what you see is the deliberate targeting of anything that will improve the quality of life of the normal Afghan citizen."
US troops make up the bulk of foreign forces in Afghanistan
Relations between the US and Pakistan - valued by the US as a key ally in the war on terror - have worsened as Washington has pressured Islamabad to take action against militants in the frontier region.
Pakistan accused US forces in Afghanistan of a "cowardly act" earlier in June when 11 of its soldiers in a border post were killed in an air strike.
Afghan officials say Taleban militants are allowed to shelter in Pakistan's tribal areas on the long, mountainous border.