By Michael Georgy and Mirwais Harooni
KABUL (Reuters) - Suicide bombers attacked a compound housing Westerners in Kabul on Wednesday hours after U.S. President Barack Obama signed a security pact during a short visit to a city that remains vulnerable to a resilient insurgency.
The Taliban claimed responsibility for the attack which involved a car bomb and insurgents disguised as women on the eastern outskirts of the capital, killing seven people, a Gurkha guard and six passers-by, and wounding 17.
The Taliban said it was in response to Obama's visit and to the strategic partnership deal he signed with Afghan President Hamid Karzai, a pact that sets out a long-term U.S. role after most foreign combat troops leave by the end of 2014.
The insurgency also claimed their spring offensive, which began two weeks ago with attacks in Kabul, would be renewed on Thursday, despite a security clamp-down in the capital.
Obama's visit came a year after U.S. special forces troops killed al Qaeda leader Osama bin Laden, the architect of the September 11, 2001, attacks, in a raid in neighboring Pakistan.
In a televised address to the American people from a base north of Kabul, he said the war in Afghanistan was winding down.
"As we emerge from a decade of conflict abroad and economic crisis at home, it's time to renew America," Obama said, speaking against a backdrop of armored vehicles and a U.S. flag.
"This time of war began in Afghanistan, and this is where it will end.
Nearly 3,000 U.S. and NATO soldiers have been killed in Afghanistan since the Taliban rulers were ousted in 2001.
The Taliban, overthrown by U.S.-backed Afghan forces for harboring bin Laden and other militants, were quick to take credit for Wednesday's attack at Green Village, one of several compounds for Westerners on a main road out of the capital.
"This attack was to make clear our reaction to Obama's trip to Afghanistan. The message was that instead of signing a strategic partnership deal with Afghanistan, he should think about taking his troops out from Afghanistan and leave it to Afghans to rebuild their country," Taliban spokesman Zabihullah Mujahid told Reuters by telephone from an undisclosed location.
But America's Kabul ambassador, Ryan Crocker, said involvement of the Haqqani network - which Washington believes is based in Pakistan's North Waziristan region and which it blames for high-profile attacks in Kabul in April - could not be ruled out.
On the anniversary of bin Laden's killing, Crocker said he did not believe there would be a sole turning point in the war.
"Al Qaeda is still there. We do feel we are prevailing in this with our Afghan partners," he said. "We cannot be in a position of taking on ourselves bringing perfection to Afghanistan. That has to be left to Afghans."
But Crocker said there would be no repeat of the 1990s when a withdrawal of Western backers in the wake of the Soviet withdrawal unleashed a vicious civil war out of which the Taliban and al Qaeda support bases arose.
Hundreds of police and intelligence agency troops surrounded the area around Green Village after the attack. Ruined cars were seen in front of the compound gates but officials said no attackers made it inside the heavily-guarded complex.
"I was going to the office when the car in front of me blew up. I got on my bicycle and fled," 40-year-old Farid Ahmad Mohammad told Reuters near the scene of the explosion.
A worker at the compound, Jamrod, said at a hospital where the wounded had been taken that he had been showing his identity card at the compound's main gate when the vehicle exploded.
"I heard a bang and then I slammed into the wall," Jamrod, still clad in blood-stained jeans, told Reuters.
Wednesday's attack was the latest in a recent surge of violence after the Taliban announced they had begun their usual "spring offensive", and since they suspended tentative steps towards peace talks with the United States.
Such incidents raise troubling questions about the readiness of Afghan forces to take over when militants remain able to stage high-profile attacks, even when already tight security had been beefed up even further for Obama's visit.
Insurgents staged coordinated attacks in Kabul last month, paralyzing the city's centre and diplomatic area for 18 hours.
The Taliban also claimed responsibility for those attacks, but U.S. and Afghan officials blamed the militant, al Qaeda-linked Haqqani network.
Obama's visit was clearly an election-year event.
He spoke to U.S. troops during a stay in Afghanistan of roughly six hours and emphasized bin Laden's demise, an event his re-election campaign has touted as one of his most important achievements in office.
"Not only were we able to drive al Qaeda out of Afghanistan, but slowly and systematically we have been able to decimate the ranks of al Qaeda, and a year ago we were able to finally bring Osama bin Laden to justice," Obama said to cheers.
But even as he asserted in his speech that there was a "clear path" to fulfilling the U.S. mission in Afghanistan and made his strongest claim yet that the defeat of al Qaeda was "within reach", he warned of further hardship ahead.
"I recognize that many Americans are tired of war ... But we must finish the job we started in Afghanistan and end this war responsibly," he said at Bagram airbase, where only months ago thousands of Afghans rioted after U.S. troops accidentally burned copies of the Koran, the Muslim holy book.
That incident, and the killing of 17 Afghan civilians by a rogue U.S. soldier weeks later, plunged already tense relations to their lowest point in years.
While speaking in broad terms of "difficult days ahead", Obama did not address some of the thorniest challenges.
These include corruption in Karzai's government, the unsteadiness of Afghan forces in the face of a resilient Taliban insurgency, and Washington's strained ties with Pakistan, where U.S. officials see selective cooperation in cracking down on militants fuelling cross-border violence.
Earlier, Obama met Karzai at his walled garden palace in Kabul, where they signed the Strategic Partnership Agreement. "By signing this document, we close the last 10 years and open a new season of equal relations," Karzai said after the meeting.
The agreement does not specify whether a reduced number of U.S. troops, possibly special forces, and advisers will remain after NATO's 2014 withdrawal deadline. That will be dealt with in a separate status-of-forces agreement still being worked out.
(Additional reporting by Rob Taylor, Hamid Shalizi and Caren Bohan; Writing by Raju Gopalakrishnan and Rob Taylor; Editing by Nick Macfie)