The United States President Barack Obama paid a sudden visit to Afghanistan on Sunday night, in a bid to boost confidence for the Afghan government and the U.S. troops stationed in the post-Taliban nation.

U.S. President Barack Obama (L) meets with Afghan President Hamid Karzai at the Presidential Palace in Kabul, capital of Afghanistan, March 28, 2010. Obama arrived unannounced in Afghanistan on Sunday, his first visit to the war zone as the U.S. President. [Ahmad Masood, Pool/Xinhua]

On his blitz tour, the U.S. president firstly had meeting with his Afghan counterpart Hamid Karzai.

During his meeting with Karzai, Obama and Karzai discussed Afghanistan's efforts of battling corruption and poppy production, which is believed to be the major financial resources of the Taliban. Obama expressed encouragement over Afghanistan's progress but urging Karzai and his government to further improve the governance and to better fight corruption.

The two leaders also exchanged views on the reintegration and reconciliation process which was launched by the Afghan government.

Obama invited Karzai to pay a visit to the U.S. on May 12.

Obama, the U.S. military commander in chief as well, had meeting with Gen. Stanley McChrystal, commander of the NATO-led International Security Assistance Force (ISAF), Afghanistan's military officials and cabinet members.

Obama later addressed the U.S. military service-members at the Bagram air base, several km off the capital city of Kabul.

The U.S. military commander in chief expressed gratitude to the U.S. troops noting that their mission in Afghanistan is "necessary and essential" for the security of the U.S. people.

U.S. lives would be at risk if the Taliban retake control of Afghanistan, Obama told the U.S. troops.

Obama said the United States would get the job done in Afghanistan in fighting against the Taliban insurgents.

He ensured the U.S. service-members of the domestic support and pledged to provide the troops with needed equipment.

Obama announced last December that he is surging 30,000 more troops into Afghanistan and will start the U.S. pullout in July 2011.

However, he did not mention the pullout date in Sunday's speech.

The United States and NATO have more than 121,000 troops in Afghanistan, set to rise to 150,000 by this August as part of the new plan to reverse the Taliban momentum, particularly in the south.

Most of the 10,000 U.S. extra troops that have arrived so far have been sent to the volatile south, the spiritual heartland of the Taliban insurgency.

Over 100 foreign troops have been killed this year.

It was Obama's first tour in Afghanistan after he took over the presidency in January 2009. He paid a visit here as a senator and a presidential candidate in 2008.

The U.S. president is expected to leave for home in the wee hours.