KABUL, Afghanistan (AP) - Six more American troops were killed in action in Afghanistan, ending August with a spike in bloodshed that has claimed the lives of 19 U.S. service members in only four days.
The U.S. death toll for the month stood at 56 - three-quarters of them in the second half of the month as the Taliban fight back against U.S. pressure in southern and eastern strongholds. American losses accounted for more than 70 percent of the 76 fatalities suffered by the entire NATO-led force.
NATO said four of the Americans who died Tuesday were killed by a roadside bomb in eastern Afghanistan, while two died in gunfights with insurgents in the country's south. No other details were released.
Until the late month spike, it appeared that the death toll for August would be well below the back-to-back monthly records of 66 in July and 60 in June.
By the middle of August only 13 Americans had been killed - in part because of greater use of heavily armored vehicles and other defenses against roadside bombs, the Taliban weapon of choice.
The reason behind the sudden spike in deaths was unclear because few details about the casualties are released for security reasons.
Most of the U.S. deaths occurred in the southern provinces of Helmand and Kandahar, longtime Taliban strongholds that are the focus of the American-led operation against the insurgents.
As the U.S. formally ends its combat role in the Iraq war, NATO and Afghan forces are ramping up operations in Afghanistan, especially in the area around Kandahar City, the Taliban birthplace and their former headquarters until they were ousted from power in the U.S.-led invasion of 2001.
NATO Secretary-General Anders Fogh Rasmussen told reporters in Copenhagen, Denmark, that higher casualties were inevitable because more troops have arrived in Afghanistan in recent weeks, bringing the overall alliance force to more than 140,000 - including 100,000 Americans. The U.S. figure is more than triple the number of American service members in Afghanistan at the beginning of last year.
"Right now we see more fighting and unfortunately also more casualties," Fogh Rasmussen said. "But that is the inevitable result of sending more troops ... On top of that, we now attack the Taliban strongholds in Helmand and Kandahar. That of course means more fighting and unfortunately also more casualties."
A NATO spokesman in Kabul, James Judge, said the insurgents traditionally step up attacks in late summer and early fall before the advent of the harsh Afghan winter, when fighting usually eases. He said casualty figures were likely to remain "somewhat elevated" in September because the insurgents may try to disrupt parliamentary elections.
In a meeting Tuesday with journalists from The Associated Press and two other news organizations, the top commander Gen. David Petraeus insisted that despite the casualties, progress was being achieved in Helmand and Kandahar. Petraeus said he recently walked through the market in Marjah, which until last February had been a major Taliban stronghold and wholesale distribution center for opium.
He said security in Kabul had been reinforced in recent months and that five or six bases were being built for the Afghan army around the city to protect the capital.
Nevertheless, gunmen stopped a bus Tuesday carrying clerks of the Afghan Supreme Court in south Kabul. One gunman boarded the bus and opened fire, killing three people and wounding 12, the Interior Ministry reported.
British Deputy Prime Minister Nick Clegg insisted Tuesday that the military campaign in Afghanistan was "turning the corner" as he wrapped up a two-day unannounced visit to British troops in Helmand.
"We hear so much bad news," he told British soldiers. "Of course the country mourns when people lose their lives. People are full of anguish when there are serious injuries. But what I have seen today is a complete transformation of the military effort that I first saw when I visited two years ago."
Also Tuesday, NATO said its forces, working with Afghan army and police, had killed 19 insurgents and captured five in a major air assault on the village of Omar in the eastern province of Kunar.
Ground forces taking part in the assault that began Monday uncovered weapons caches and ammunition stockpiles inside the village, a statement said.
Two insurgents were killed and one was wounded in an airstrike Monday on a Taliban commander in charge of logistics in Kandahar, NATO said.
In Zabul province, insurgents on Monday night ambushed a convoy carrying food and other supplies, killing two private security guards and wounding five others, provincial government spokesman Mohammad Jan Rasoolyar said.