KABUL, Afghanistan (AP) – Flying fast and low, U.S. helicopters skimmed just above dusty fields dotted with bombed-out remnants of war. Door-gunners gripped machine guns, watching for any threat from the ground or the air. The mission: Safely ferry President Bush on his surprise visit to boost Afghanistan’s fragile democracy.

Violence and suicide bombings are on the rise in Afghanistan, and Bush would be a prized target for al-Qaida and Taliban militants driven into hiding by the U.S.-led invasion. This is the country where Osama bin Laden trained terrorists and plotted the attacks against America on Sept. 11, 2001.

Bush seemed unfazed by the security risks as he moved quickly around Kabul for four hours, meeting with President Hamid Karzai, U.S. Embassy workers and American and foreign forces at Bagram Air Base.

He expressed unwavering confidence that bin Laden will be captured despite years of fruitless manhunts for the elusive terrorist leader who ran training camps in Afghanistan and 9/11 attacks.

Bush ordered Air Force One, on a flight to India, to make a secret detour to this war-scarred country to show U.S. support for the fledgling democracy led by Karzai, whose authority has been weakened by suicide bombings and rising violence by insurgents.

There are more than 18,000 U.S. forces in Afghanistan, and Bush said their mission was “to help this new democracy not only survive but to flourish.”

The president, who once boasted bin Laden would be taken “dead or alive,” said the fugitive terrorist would not elude the United States forever. Bin Laden and Taliban leader Mullah Omar were driven into hiding by the U.S.-led invasion of Afghanistan after 9/11. They are believed to be in the rugged Pakistan-Afghan border region.

“It’s not a matter of if they’re captured and brought to justice,” Bush said at a news conference with Karzai at the war-worn presidential palace. “It’s when they’re brought to justice.”

Eight weeks in the planning, Bush’s visit to Afghanistan was not announced in advance to reduce chances of an assassination attempt. Heavily armed combat-assault teams shadowed Bush’s moves. Door-gunners on at least two helicopters fired a brief burst of bullets down at the dusty flatlands not far from Bagram Air Base as they ferried the president’s entourage into town. A White House official suggested it was test fire.

Streets were locked down and there was a heavy show of security along Bush’s brief motorcade route. There was no other traffic. At one intersection, pedestrians gawked from behind military and security forces.

It was Bush’s second visit to a war front, after his secret trip to Iraq to visit with U.S. troops at Thanksgiving in 2003.

Karzai said Afghanistan owes the United States “a great, great deal in this country’s rebuilding – peace, democracy, the strong steps toward the future.”

Bush said Karzai’s government, which has allowed young girls to attend school, is one that believes in hope – “which is the exact opposite of the ideology of the bin Ladens of the world and the Taliban.”

Bush spent just four hours in Afghanistan, racing from meetings and lunch with Karzai, the news conference, a ceremonial ribbon-cutting at the new U.S. Embassy and a pep talk for 500-600 U.S. and foreign troops at Bagram Air Base.

From Afghanistan, Bush flew to India for two days of appointments that both sides hope will be capped by a landmark civilian nuclear agreement. Bush said it was a difficult issue for both countries, and one official suggested that if there were to be an agreement, it would come at the last moment.

The president is to fly to Pakistan on Friday evening and return to Washington late Saturday.

At the news conference, Bush and Karzai spoke of the steps Afghanistan has made toward rebuilding the nation, restoring peace and achieving democratic reform. But Bush acknowledged Afghanistan’s complaints about violence emanating from neighboring Pakistan, and said he’d talk with Pakistani President Gen. Pervez Musharraf about it when he sees him in Islamabad.

As Bush arrived in South Asia, Pakistani security forces struck a militant training camp near the Afghan border, killing three dozen fighters, including a Chechen commander linked to al-Qaida, an army official said. Pakistan, a key U.S. ally in the war against terror that has deployed thousands of troops to fight militants, has denied in the past that arrests of militants are timed to coincide with events.

“I absolutely will bring up the cross-border infiltrations with President Musharraf,” Bush said. “These infiltrations are causing harm to friend, allies and cause harm to U.S. troops.”

Bush said he also would remind Musharraf about the need to capture bin Laden and Omar. “It’s important that we bring these people to justice,” Bush said. “He (Musharraf) understands that. After all, they’ve tried to kill him four times.”

Violence in Afghanistan increased 20 percent last year, the Defense Intelligence Agency said this week. About 1,600 people were killed in violence last year, including 91 U.S. troops. There have been 25 suicide bombings in the past four months.

It was Bush’s first visit to Afghanistan although his wife, Laura, and Vice President Dick Cheney both have visited here before. The first lady joined her husband.