President Obama is shown in a meeting discussing the mission against Osama… (Pete Souza / White House )
WASHINGTON -- President Obama arrived in Afghanistan today, marking the one-year anniversary of the killing of Osama bin Laden with an unannounced visit to meet with the Afghan president and sign a strategic partnership agreement between the two nations.
Obama is scheduled to address the nation from Bagram Air Base at 4:30 p.m. PDT to discuss the agreement.
The president's trip marking the May 2 anniversary of the Bin Laden killing was arranged in secrecy. Obama left from Andrews Air Force Base outside Washington just after midnight EDT, arriving at Bagram at 10:20 p.m. local time. From there he traveled to the presidential palace in Kabul, arriving just after 11 p.m.
The visit is Obama's first to the country since December 2010, when he addressed U.S. forces at Bagram.
The trip took place under strict White House security measures, precluding journalists with Obama from reporting on the visit until the president arrived at the presidential palace on Tuesday.
During the visit, Obama and Afghan President Hamid Karzai signed a 10-page strategic partnership agreement. In it, the U.S. pledges support for Afghanistan lasting a decade beyond 2014, when NATO forces are due to end their combat role in the country.
For security reasons, the military and Secret Service prefer to keep the president's travel in a war zone, particularly arrivals and departures, under cover of darkness.
But the timing of this trip also allows Obama to address the national during the major broadcast TV networks' prime-time viewing hours.
Though the trip is taking place around the one-year anniversary of the killing of Bin Laden, senior administration officials said the timing owes to the progress in negotiations about the strategic partnership agreement.
Both presidents wanted to sign the agreement in Afghanistan, U.S. officials said, in advance of the upcoming NATO summit in Chicago.
Before he addresses the nation, Obama plans to meet with U.S. troops at the Bagram base.
The trip comes a day after the president denied any "excessive celebration" of the Bin Laden killing on the part of his administration. Republicans have accused him of politicizing the anniversary.
On Monday, presumptive GOP presidential nominee Mitt Romney rejected the Obama campaign's questioning of whether he would have authorized the same high-risk raid to capture or kill Bin Laden, saying any president, even Jimmy Carter, would have done so.