The United States has designated Afghanistan a major non-NATO ally - a status that provides a long-term framework for military co-operation and gives Kabul preferential access to US arms exports.
The announcement was made by the US Secretary of State, Hillary Clinton, during a brief visit to Afghanistan ahead of an aid conference in Japan.
The US has committed billions of dollars a year to Afghanistan after NATO troops pull out in 2014, the BBC reports.
Mrs Clinton says she wants to see a strengthened Afghanistan so the local people can take responsibility for their lives and where Afghan children can grow up in peace and stability.
Her visit comes the day before a major conference of Afghanistan's foreign donors in Japan, which is expected to discuss how to support the country once international troops leave.