U.S. troop killed in Afghanistan attack amid fears that militants regrouping in rugged eastern areas along Pakistan border

KABUL, Afghanistan Taliban insurgents killed 10 Afghan troops in an ambush in western Herat province, police and government officials said Tuesday, as one U.S. troop was killed in an attack on the other side of the country.

A statement from the U.S.-led international military coalition said an American service member died following an unspecified insurgent attack Tuesday in eastern Afghanistan. The exact location and nature of the attack were not given, but it comes as Afghan leaders in some eastern provinces voice concerns that al Qaeda and Taliban militants may be gaining territory and momentum more than two years before Western combat troops are scheduled to be pulled out of the country.

The latest death makes at least 12 American service members killed so far this month and 265 killed so far this year.

While 10 years of ground war and aerial bombardment have seriously weakened al Qaeda in Afghanistan, the governors of two remote eastern provinces, Kunar and Nuristan, said Tuesday that they already see signs that Taliban and al Qaeda militants are ramping up operations and claiming more territory.

Tamim Nuristani, the governor of Nuristan, told CBS News Kabul bureau chief Fazul Rahim that the situation in much of his province is, "out of control."

Nuristani said that, with the exception of the provincial capital and surrounding areas, the rest of the province is under the control of or completely surrounded by the Taliban. He added that, although most of the militants fighting the government are local Afghan Taliban, there is also a heavy presence of foreign militants -- including al Qaeda and their allies in the Pakistani Taliban (TTP). The governor said there are not enough troops to deal with the threat and if the central government does not act decisively, the mountainous province could become a safe haven for terrorists even before the U.S. withdrawal.

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Sayed Fazlullah Wahedi, governor of neighboring Kunar province, said overall the situation in Kunar is "satisfactory" right now, but due the province's location on the rugged, mountainous border with Pakistan, it is hard for the available Afghan security forces to try and keep watch over the entire region. Wahedi did not give specific numbers, but he said there is heavy presence of foreign fighters affiliated with al Qaeda and the TTP, as well as Afghan Taliban, in certain parts of Kunar. Like his counterpart in Nuristan, Wahedi said there are not enough troops -- be they Western or Afghan -- to counter the threat that already exists in his Kunar, and he fears it will only get worse as NATO troops head home.

The Herat ambush, meanwhile, was the bloodiest single incident for Afghan security forces this year in western Afghanistan -- an area where the insurgents have been less active than in their strongholds in the east and south of the country.

In recent months, Taliban guerrillas have been switching tactics and increasingly targeting Afghan security forces as the international coalition continues its drawdown toward a planned withdrawal of the majority of combat troops in 2014.

A spokesman for the provincial governor in Herat, Muhiudin Noori, said the Afghan troops, which included both soldiers and police, were searching late Monday for a group of insurgents who had earlier set up a roadblock, stopping and seizing passing vehicles, when they were ambushed.

Five policemen, including the district commander and five soldiers died in the ensuing firefight, Noori said. There were no insurgent casualties, but police later arrested 25 suspects found in the area, he said.

Meanwhile, President Hamid Karzai condemned "in the strongest possible terms" a NATO raid on Sunday in Logar province, in the east, in which he said four children were killed.

A presidential statement said coalition troops carried out the operation in Baraki Barak district in an effort to apprehend two armed militants. But this resulted in the deaths of the four children who were tending to their animals in the same area, it said.

Din Mohammad Darwesh, spokesman for the provincial governor, said the victims were between 10 and 13 years old.

NATO on Tuesday acknowledged that its forces "may be responsible for the unintended, but nonetheless tragic, death of three Afghan civilians" during the operation in Baraki Barak district. Coalition commander U.S. Gen. John R. Allen expressed his condolences to the families of those killed.

There was no immediate explanation for the discrepancy in the number of victims in the two statements.

In recent months, Karzai has criticized the international military coalition for what he said was the killing of civilians in Afghanistan, for not going after terrorist safe havens in neighboring Pakistan and for not providing the Afghan forces with all the weapons they need.

The criticisms drew an angry response from U.S. Defense Secretary Leon Panetta, who earlier this month said the Afghan leader should occasionally say "thank you" to allied forces who are fighting and dying in Afghanistan, rather than criticizing them.