Afghanistan will become a major non-NATO ally for the US, Hillary Clinton, the secretary of state, has said during a visit to Kabul.
The designation, which provides a long-term framework for security and defence co-operation, would give the war-torn country special privileges as the US prepares to pull its troops out in 2014, Clinton said on Saturday.
"We see this as a powerful symbol of our commitment to Afghanistan's future," Clinton said at a press conference after talks with President Hamid Karzai.
"This is the kind of relationship that we think will be especially beneficial as we do the transition."
The new status, which comes into effect immediately, makes it easier for a country to purchase and finance its acquisition of US defence equipment, along with other benefits.
"The United States is not abandoning Afghanistan," Clinton said. "Quite the opposite: we are building a partnership with Afghanistan that will endure."
Najeeb Azizi, professor at Kabul university, told Al Jazeera that the move had come at an opportune time for Afghanistan.
"The Afghans have been having a lack of trust towards the international community especially towards the US, [they] have been confused in regards to what will happen to Afghanistan beyond 2014," he said.
"The explanation of Ms Clinton is coming at a special juncture of time - it is just one day before the Tokyo conference and Ms. Clinton is mentioning what is in fact the status of Afghanistan as the non-NATO ally of the US.
"It means a greater support for the Afghan military forces, the Afghan government will be able to purchase and import the weaponry from the US without a lot of restrictions and it is another confidence building measurement for the Afghan government."
Clinton travelled to Afghanistan from France where she had been attending a "Friends of Syria" conference, which attracted more than 100 nations.
This is the first such designation by President Barack Obama's administration. Other countries with the designation include Pakistan, Israel, Egypt, Japan, Jordan Korea, Argentina, Australia and New Zealand.
Clinton said the security situation in Afghanistan "though far from ideal, is certainly more stable", while the capacity of the Afghan security forces had "significantly improved".
NATO leaders have endorsed plans to hand Afghan forces the lead for security across their country by mid-2013 while foreign troops will gradually switch their focus from combat to support mode.
NATO has a total of 130,000 soldiers helping the Karzai government fight the Taliban, and they are due to withdraw by the end of 2014 when the transition process is complete.
The US and Afghanistan have already signed a Strategic Partnership Agreement which includes commitments on promoting democracy, good governance, advancing long-term security with the provision of foreign funds for the Afghan forces.
Clinton's visit to Kabul was a three-and-a-half hour stopover on her way to a major conference in Tokyo in which Afghanistan is set to seek billions of dollars in civilian aid.
Karzai, who will be in Tokyo along with Clinton and United Nations chief Ban Ki-moon, has called for some $4bn a year in civilian aid for Afghanistan to be pledged during Sunday's conference.
But a principle of "mutual accountability" will be stressed at the 70-nation meeting, making continued payment of aid conditional on Kabul making progress, particularly on corruption and transparency.
"Whilst [the NATO summit in] Chicago sought to show the beginnings of the implementation into transition, the transformation decade, on the security side, the goal of Tokyo is to [do] that same piece on the economic side, the civilian side," a US official said.