KABUL, Afghanistan (AP) — Roadside bombs killed seven American troops on Monday — including five in a single blast in Kandahar — raising to more than a dozen the number who have died in the last three days.

The spike in deaths comes as President Hamid Karzai has publicly raised doubts about the U.S. strategy in the war, saying success cannot be achieved until more Afghans are in the front lines and insurgent sanctuaries in Pakistan are shut down.

NATO gave no details of the Monday blasts except that they occurred in the south, the main theater of the conflict, and that five were killed in a single blast.

Witnesses said the five died when a bomb struck a Humvee on a main road on the outskirts of Kandahar, the focus of an ongoing military campaign to secure the city that the Taliban used as their headquarters during their years in power. The attackers apparently targeted the Humvee because it was not as heavily armored as other vehicles in the convoy.

Later Monday, a pair of rockets were fired at the Kandahar offices of the U.N. mission in Afghanistan. One fell short and slightly wounded a guard. The other overshot the compound and exploded in an empty field, police said.

U.S. death tolls for August had been running well behind those of the previous two months that set monthly records — 60 in June and 66 in July. But 14 Americans have been killed in the last three days, raising the American U.S. toll for the month to 49, most of them in the south.

NATO commanders have warned that casualties will mount as coalition and Afghan forces enter areas that have been under longtime Taliban control. The NATO force swelled this month to more than 140,000 — including 120,000 Americans — with the arrival of the last of the reinforcements that President Barack Obama ordered to Afghanistan in a bid to turn the tide of the nearly 9-year war.

With death tolls rising, Karzai has become more outspoken in his criticism of the U.S.-led war effort, telling recent visitors that the American counterinsurgency strategy is flawed.

Most recently, he told the visiting speaker of the German parliament that the campaign against the Taliban over the last eight years had been "ineffective apart from causing civilian casualties," according to a statement by the presidential media office.

The statement quoted Karzai as saying Afghan forces should take the lead in efforts to win support from deeply conservative Afghan villagers who harbor suspicion of outsiders. That appears at odds with the strategy pursued by the top NATO commander, Gen. David Petraeus, which calls for U.S. troops to live closer to villagers to win their trust and protect them from the Taliban.

Last week, Karzai told a group of visiting U.S. congressmen that Obama's plan to begin withdrawing U.S. troops in July 2011 had given a "morale boost" to the Taliban and that the war could not be won until insurgent sanctuaries across the border in Pakistan are eliminated.

Meanwhile on Monday, a district governor in the eastern province of Nangarhar, Sayad Mohammad Palawan, was killed when a bomb planted on his vehicle exploded as he was driving into a government compound in Jalalabad for a meeting of provincial security and political leaders, according to police spokesman Ghafor Khan.

Insurgents apparently planned for the bomb to explode inside the compound where it could potentially have caused far greater destruction, Khan said.

Elsewhere, NATO announced the arrest of an insurgent commander and several associates believed involved in a weekend attack on two NATO bases in Khost province of southeastern Afghanistan. Nearly 50 insurgents were killed in simultaneous attacks Saturday on Forward Operating Base Salerno and nearby Camp Chapman, where seven CIA employees died in a suicide attack in December.

The commander was believed to be a member of the Haqqani network, a Pakistan-based faction of the Taliban with close ties to al-Qaida.

Afghanistan's Defense Ministry reported Monday that four Afghan soldiers were killed and another wounded the day before in a roadside bombing in Wardak province. A fifth Afghan soldier was killed and another hurt in a bombing in Helmand province's Nad Ali district.

In the southeastern province of Zabul, 24 Taliban traveling by truck and motorcycle were captured while trying to cross the border into Pakistan, said provincial government spokesman Mohammad Jan Rasoolyar.

Five Taliban, including one regional commander, were also killed in fighting with coalition forces Sunday in Helmand province's Gereshik district, according to Daoud Ahmedi, spokesman to the provincial governor.


Associated Press writer Mirwais Khan contributed to this report from Kandahar.