BAGHDAD - U.S. Secretary of State Hillary Rodham Clinton on Saturday assured Iraq that the Obama administration would not abandon the country even as it presses ahead with plans to withdraw American troops amid a recent surge in violence.

Clinton, on an unannounced trip to Baghdad, said the drawdown would be handled in a "responsible and careful way" and would not affect efforts to improve the professionalism of Iraq's security forces or reconstruction and development projects that are to be expanded.

But she stressed that Iraqis themselves particularly within the security forces would have to come together and overcome sectarian and other differences if they are to build a united, secure nation.

"Let me assure you and repeat what President Obama said, we are committed to Iraq, we want to see a stable, sovereign, self-reliant Iraq," she told a nervous but receptive crowd at a town hall meeting at the U.S. Embassy here.

"We are very committed, but the nature of our commitment may look somewhat different because we are going to be withdrawing our combat troops over the next couple of years," Clinton said.

Making her first trip to Iraq as America's top diplomat, Clinton said the country has made great strides despite an explosion in violence that killed at least 159 people on Thursday and Friday.

Ahead of her arrival, Clinton said the attacks are a sign that extremists are afraid the Iraqi government is succeeding.

Clinton arrived a day after back-to-back suicide bombings killed 71 people outside the most important Shiite shrine in Baghdad. Those attacks came after Iraq on Thursday was rocked by its most deadly violence in more than a year when 88 people were killed by suicide bombers in Baghdad and Muqdadiyah.

Although the violence is at its lowest levels since the months following the 2003 U.S.-led invasion, the latest bombings come amid an increase in high-profile sectarian attacks that have raised concerns about the abilities of Iraq's security forces.

They have exposed gaps in security as Iraq takes over from U.S. forces in protecting the country and Iraqi Prime Minister Nouri al-Maliki has ordered a military task force to investigate the attacks as well as shortcomings that allowed the assailants to slip through. The government also ordered heightened security at major Shiite shrines across the country.

The Pentagon plans to hand over responsibility for most urban security in about three months as part of the administration's goal of a complete exit of forces by the end of 2011.

U.S. officials say they are still committed to a June 30 deadline to move all forces outside major cities, including Baghdad.