A U.S. soldier was killed Tuesday when a bomb exploded near a troop patrol in volatile eastern Afghanistan, while President Hamid Karzai said he expects terror attacks to continue in his country "for much more time to come."

The attack occurred a day after homicide bombers rammed cars filled with explosives into NATO peacekeepers in two attacks in the Afghan capital — the first major assault on foreign troops in Kabul in more than a year. The death toll rose to nine Tuesday as police found more bodies in a ditch and a wounded man died.

Police blamed Al Qaeda for the homicide bombings. Such seemingly coordinated attacks are unprecedented in Afghanistan and reinforced fears that Usama bin Laden's terror network has teamed up with its old ally the Taliban, which claimed responsibility for the attacks.

On Wednesday, a militant rammed his car into a convoy of four-wheel-drive Toyota Landcruisers before detonating explosives, Gov. Asadullah Khalid said. No one traveling in the convoy was wounded, but a passer-by was killed and four others injured, he said.

U.S. military spokesman Lt. Col. Jerry O'Hara said initial reports indicated that U.S.-led coalition troops were providing security to the convoy, but no soldiers had been wounded and no equipment damaged. He said it was not immediately clear who was inside the convoy.

In Tuesday's violence, U.S. and Afghan troops were traveling in an armored vehicle in Paktika province near the Pakistani border when the roadside bomb exploded, killing an American soldier. The blast also wounded another U.S. soldier, two Afghan soldiers and a civilian, the military said.

This year has been the deadliest for U.S. troops in Afghanistan since the Taliban was ousted in 2001. At least 87 U.S. military personnel have been killed or died in accidents. Nearly 1,500 Afghan civilians, security forces and rebels also have died.

Militants also fired two rockets into Kabul late Tuesday, landing one about half a mile from the headquarters of NATO peacekeepers, said Lt. Col. Cristoni Riccar, a spokesman for the force. No casualties were reported.

Karzai said he expects the violence to continue.

"Terrorism will remain to affect us, will remain to attack us, for much more time to come," Karzai told reporters while attending an Islam conference in Austria. "What is important for us right now is to continue to ... strengthen democratic institutions."

Asked about the new suspected link between Al Qaeda and the Taliban, Karzai said the two groups never ceased to cooperate.

"It's the same thing — it's terrorists," he said.

Monday's bombings appeared to be part of a new campaign by militants to use suicide assailants in Afghanistan. Until two months ago, they were relatively rare here, unlike in Iraq. But since then, eight such assaults have been used nationwide.

Investigators recovered parts of the bodies of the two bombers in Kabul and said the attackers appeared to have been Arabs, police commander Gen. Mohammed Akbar said.

"Al Qaeda is definitely behind this attack," he told The Associated Press. "Only Al Qaeda has the capability to do this."

A Taliban commander in southern Kandahar province, Mullah Ahmadullah Jan, said some Arab fighters with links to Al Qaeda have joined the ranks of the rebels.

"We have more than 300 Taliban who have registered themselves to carry out suicide attacks," he said by satellite telephone. "Nearly all are Afghans."

The claim could not be independently confirmed. Taliban commanders, as well as their spokesmen, often make claims that later prove exaggerated or untrue.

The death toll from Monday's bombings rose to nine after police found six more burned bodies lying in a ditch and a man who was initially wounded died in a hospital, officials said. Two people were confirmed dead on Monday — a German peacekeeper and an Afghan child.

The bombings occurred within 90 minutes of each other near the headquarters of Afghan-U.N. election organizers. Troops thwarted a suspected third bombing by fatally shooting three people in a car racing toward the scene of the blasts.

Fearing more bombings, police set up roadblocks around the city Tuesday and searched houses for militants, while peacekeepers in helicopters hovered low to spot suspicious activity.

Some international aid groups restricted the movement of their staff. U.N. spokesman Adrian Edwards said the world body had gone to a heightened state of alert and only essential staff were allowed to come to work.