The United States has declared Afghanistan a "major non-Nato ally" in a move which will make it easier for closer military co-operation, including access to weapons and training.
US Secretary of State Hillary Clinton made the announcement during a surprise visit to Kabul for talks with Afghan President Hamid Karzai.
The declaration allows for streamlined defence co-operation, allowing Afghanistan to buy US weapons and have ease export control regulations.
Afghanistan's military, which is heavily dependent on American and foreign assistance, already enjoys many of these benefits. The non-Nato ally status guarantees it will continue to do so.
"We see this as a powerful commitment to Afghanistan's future," said Mrs Clinton at a news conference in the grand courtyard of the Afghan capital's presidential palace.
"We are not even imagining abandoning Afghanistan," she added, in a strong show of support, with US combat troops set to withdraw from the country in 2014.
Fighting still rages in the war-torn country as Afghan and US-led Coalition forces battle insurgents mostly in the eastern part of the country.
More recently, three British soldiers were killed after a man wearing an Afghan police uniform shot at them at a checkpoint in Helmand province on July 1.
Although casualties have fallen among foreign forces as the US and other nations begin a gradual withdrawal, 215 Coalition soldiers were killed in the first six months of the year - compared to 271 in the same period last year.
US President Barack Obama's decision meets a pledge he made on a visit to Afghanistan earlier this year to upgrade Kabul to a special security status given to only a limited number of countries including Israel and Japan. Pakistan was the last nation to gain the status in 2004.
The meeting between Mrs Clinton and President Karzai took place before the pair jetted off separately for a conference in Tokyo, where representatives from some 70 countries, including Britain, are expected to gather to discuss civilian aid to Afghanistan.
Nations that once gave more generously to Afghanistan are now seeking guarantees that their taxpayer money will not be lost to corruption and mismanagement.
Donors at Sunday's meeting are expected to commit just under \$4bn (£2.5bn) annually in development aid for Afghanistan.