KABUL, Afghanistan>> A wave of violence killed six U.S. troops and at least a dozen civilians Saturday in Afghanistan’s volatile south and east, as American reinforcements moving into Taliban-dominated areas face up to the fierce resistance they expected.

Increased U.S.-led military operations in the southern province of Kandahar are aimed at trying to break the Taliban’s grip where they are strongest by delivering security and government services to win over Afghan people.

The hope is that once the tide begins to turn, more control can be handed to Afghan forces without fear that the Taliban might again seize power, bring back its harsh interpretation of Islamic law and resume sheltering al-Qaida terrorist leaders. Then U.S. troops could begin withdrawing in July 2011, in line with a timeline set by President Barack Obama.

Senior U.S. military officers have warned, however, that the fight in the Taliban’s spiritual birthplace would lead to a rise in casualties for troops. June was the deadliest month of the nearly 9-year-old war, and July has kept pace.

On Saturday, two of the U.S. troops killed died in the south in separate roadside bombings. In Kandahar city, a remote-controlled bomb on a motorcycle exploded, setting cars ablaze and shattering windows at a popular shopping center. The provincial government said one passer-by was killed.

The other American service members died in the east: One as a result of small-arms fire, another by a roadside bomb, a third during an insurgent attack and the last in an accidental explosion. Their deaths raised to 23 the number of American troops killed so far this month. Last month, 103 international troops were killed, 60 of them Americans.

In the spring, as NATO began stepping up patrols in the south, Adm. Mike Mullen, head of the Joint Chiefs of Staff, warned reporters again that such a rise casualties would be inevitable. “I think we’ve been very clear for months now that this was going to be a very difficult fight in the south, and tried to set expectations, as tragic as it is, for these losses,” said Mullen, who is Obama’s top military adviser.

Progress has indeed proved slow, and the Afghan government is struggling to build trust, with many authorities seen as corrupt or unprofessional. Violence has also escalated as the insurgents work to sabotage Afghan authorities and kill foreign forces, sometimes with dramatic terrorist attacks, but most days with a steady flow of roadside bombs and small attacks.

In Saturday’s deadliest attack, eastern border province of Paktia, unidentified gunmen killed 11 Pakistanis who had crossed into Afghanistan to buy supplies, according to Rohullah Samon, spokesman for the provincial governor.

Samon said 11 Shia minority Muslim tribesmen died and three people, including a child, were wounded in the ambush of their minibus in Chamkani district.

Elsewhere in Paktia, Afghan and international forces also said a combined commando unit killed a Taliban operative and captured eight others in an overnight raid, though local villagers later staged a small protest, saying the men were innocent civilians.

Another, larger protest in the northern city of Mazar-i-Sharif involved another night raid that killed two security guards near a market earlier in the week.

A crowd of more than 1,000 crowd chanted “Death to America! Long live Islam!” Protesters said the security guards were unjustly killed when combined Afghan and international forces landed by helicopter at the bazaar before dawn Wednesday.

NATO spokesman Col. Wayne Shanks said the two guards were shot when they raised their weapons at the commandos and refused orders to put them down. He said the raid succeeded in capturing a Taliban-allied operative who supplied bomb-making material.

The international coalition has been aggressively stepping up such raids, trying to break up Taliban leadership and operations capability in a renewed push as 30,000 more American troops arrive to try to turn around the war.

The coalition say commando units have captured more than 100 senior and midlevel Taliban figures since April and killed dozens more. But the success rate has not made much of a dent in insurgent attacks.

On Saturday, an explosion tore through a NATO convoy traveling in the eastern province of Khost, though no one was killed. The German army later said two of its soldiers were slightly wounded by a roadside bomb in the northern province of Kunduz — the second homemade explosive attack on German troops in the area that day.

NATO’s International Security Assistance Force has been in Afghanistan since shortly after the fall of the Taliban in 2001, when U.S.-backed forces toppled the regime that sheltered the al-Qaida terrorist leadership following the Sept. 11 attacks in the United States.