Kabul, Afghanistan ? Assailants fired a rocket at an American helicopter taking President Hamid Karzai on a rare foray into Afghanistan’s troubled provinces Thursday, but it missed and he escaped injury.

Karzai has survived at least one previous attempt on his life. He made light of the attack, which renewed concern about the U.S.-backed leader’s safety amid Taliban threats to derail the Oct. 9 presidential election.

Officials arrested three suspects.

The U.S. military said the rocket missed the chopper as it approached a landing zone near the city of Gardez, 60 miles south of Kabul. Karzai planned to open a school in Gardez.

“The rocket was fired at the helicopter as it was landing, and missed,” U.S. spokesman Maj. Mark McCann said.

The helicopter did not touch down, and returned the president to Kabul. Two lumbering Chinooks escorted by helicopter gunships were seen shortly before noon over the downtown area.

No one was hurt by the attack, either on the ground or in the air, presidential spokesman Jawed Ludin said.

Ludin said the rocket came down in a village about a mile from Gardez. However, McCann and the local governor said the impact site was only about 500 yards from the landing zone.

By Thursday evening, Ludin said investigators had found the launch site in Rabat, just west of Gardez. Residents helped them track three people on two motorcycles to a nearby village, where the three were arrested.

“We’re still investigating to find out who they are and where they came from,” Ludin said.

After he escaped a rocket attack on his helicopter, Afghan President Hamid Karzai returned to Kabul, Afghanistan, and answered questions at a news conference. No one was hurt in Thursday's attack in eastern Afghanistan, where Karzai was traveling to mark the opening of a school.

Remnants of the former Taliban regime have waged a stubborn insurgency against Karzai’s administration and foreign forces. This year, more than 900 people have been reported killed in political violence.

In an effort to protect against additional political violence, the Pentagon has ordered about 700 airborne soldiers to deploy to Afghanistan to provide security before the election, U.S. military officials said Thursday in Washington. The troops will come from the 82nd Airborne Division at Fort Bragg, N.C., and will reinforce the 18,000 coalition forces already in the country, they said.

Officials are bracing for a surge in violence ahead of the election, which Afghanistan’s international sponsors hope will cement the shaky peace process begun after the United States ousted the Taliban in 2001 for harboring Osama bin Laden.

Karzai dropped a powerful anti-Taliban faction leader as his running mate and took advantage of a burst of infighting in the west to oust the region’s strongman.

The aborted school opening was a setback for Karzai, who is trying to muster a majority in the ballot and avoid a runoff.