Updated

KABUL, Afghanistan -- Vice President Joe Biden has landed in Kabul on an unannounced visit to Afghanistan to assess the transition from a NATO-led to an Afghan security force beginning in July 2011, when the U.S. plans to reduce its presence.

Biden also intends to demonstrate U.S. commitment to a long-term partnership with Afghanistan during his trip. He will meet with President Hamid Karzai, visit with U.S. service members and civilian personnel at the U.S. Embassy and visit an Afghan Army training center.

This is Biden's first trip to Afghanistan as vice president. He last visited the country in January 2009 while vice president-elect.

Biden will also meet with Gen. David Petraeus, the head of U.S. forces in Afghanistan and Amb. Karl Eikenberry.

A senior administration official traveling with the president called the transition "a pivot point" in U.S. policy aimed at an Afghan lead this year that will end in a full takeover in 2014.

Biden's surprise visit Monday evening comes a little more than a month after President Obama traveled to Afghanistan, where he thanked the U.S. troops who comprise the bulk of a 140,000-strong NATO force fighting terrorist organizations there.