KABUL, Afghanistan – The United States began its withdrawal from Afghanistan in earnest, officials said Monday, sending the first of what will be tens of thousands of containers home through a once-blocked land route through Pakistan.

The shipment of 50 containers over the weekend came as a new U.S. commander took control of U.S. and NATO forces in Afghanistan to guide the coalition through the end stages of a war that has so far lasted more than 11 years.

The containers were in the first convoys to cross into Pakistan as part of the Afghan pullout, said Marcus Spade, a spokesman for U.S. forces in Afghanistan.