Meanwhile, the American envoy to Afghanistan says U.S.-led forces have moved into a "manhunt phase" in the fight against al Qaeda but remain concerned that scattered elements could sow enough chaos to undermine Afghanistan's tentative stability.
"They're a threat. I suspect they're not happy about what's happening in Afghanistan," said Zalmay Khalilzad, President Bush's special representative. "We have al Qaeda on the run, but the movement remains dangerous. And the risk of future attacks cannot be excluded."
And more than 200 Turkish troops landed in the Afghan capital just after dawn Tuesday, the main body of an expanded contingent that will take command of the international force guarding Kabul later this month.
A Canadian military spokesman said only two of the rockets, launched at dawn with a time-delay mechanism, managed to get within a mile of Kandahar air base and its runway, the apparent target.
"A rocket attack was launched in direction of the Kandahar airfield and missed its target," said Canadian Navy Lt. Luc Charron.
Charron said six rockets had been aimed at the base, but two misfired and two fell short just 300 yards from the launch site and did not detonate. They were found by a Canadian patrol and its combat engineers destroyed all four missiles.
"The investigation is still ongoing," Charron said.
The 107mm rockets were apparently Chinese-made and similar to ones used in an April attack against the base.
It was the second attack in the Kandahar area in three days. Kandahar is in the middle of an election for delegates to represent Afghanistan's southern provinces at the national grand council, or loya jirga, that will select a new government in Kabul from June 10-15.
In a wide-ranging, hour-long news conference that offered a snapshot of U.S. policy in the region on the eve of change, Khalilzad said Washington was optimistic that the upcoming loya jirga will be fair and representative.
Invoking the U.S. role in overthrowing the Taliban and helping Afghanistan get back on its feet, Khalilzad stood in blistering sun at the foot of the heavily guarded U.S. Embassy's front steps, an American flag at his side.
He called on the next administration, which will govern for 18 months under a U.N. blueprint for Afghanistan's immediate future, to offer a "stable equilibrium" between central government and regional concerns.
Such a balance, he said, can help prevent warlords from running the show and shoving Afghanistan back into the factional chaos that has plagued it for two decades.
"This country's fragmented. What's needed is for a state to be built that is a balance between the powers of the center, the new government that's being built, and the regions," he said. "What that exact balance will be is for the Afghans to decide."
Khalilzad underscored several times the U.S. view that while the international community must continue to help Afghanistan militarily and economically, Afghans must chart their future. Such an outlook dovetails with the Bush administration's wariness of involving American troops in so-called "nation-building."
Work gangs Tuesday spruced up stone walls in Kabul with white paint and splashed fresh tar on a pockmarked road leading to the site of next week's Loya Jirga.
The tightened security that international forces patrolling Kabul say has been put in place to ward off attacks by remnants of the ousted Taliban or the al Qaeda Islamic militant network was, however, less evident.
On main roads leading into the capital where the 1,501 Loya Jirga delegates will meet, soldiers manning customary military checkpoints made cursory checks on passing vehicles, looking for visible weapons, and then waved them on.
Inside the city of two million people, police at some roundabouts and intersections did the same to the furious honking of drivers stuck in unfamiliar traffic jams.
The Turkish soldiers arrived on a civilian Airbus at the military side of Kabul Airport and filed off the plane with bags and briefcases but no guns. They were greeted in a receiving line by Turkish troops already stationed in Kabul as part of the International Security Assistance Forces.
The 18-nation ISAF contingent, which now numbers 5,000, has been charged with keeping order in Kabul since January. Though it is part of a U.N. mandate, it does not consist of blue-helmeted U.N. peacekeepers. Instead, forces from the different nations work together under an umbrella command.
That command has been held by Britain, but later this month, British ISAF commander Gen. John McColl is to hand the reins to Turkey. Turkish forces and advisers have been arriving piecemeal in recent weeks, but the group that arrived Tuesday was the largest to date.
In addition to guarding the capital, ISAF forces will help a new, specially trained Afghan National Guard unit protect the city next week during the loya jirga, the grand council meeting to pick a transitional government for Afghanistan.