US Secretary of State Blinken and his Qatari counterpart Al Thani signed an agreement making Qatar the US' representative in Afghanistan.
The United States has agreed to set up an interests section in Qatar's embassy in Afghanistan to assist US citizens following the shuttering of the US embassy during the Taliban takeover.
Welcoming his Qatari counterpart to Washington on Friday, Secretary of State Antony Blinken signed an agreement that established Qatar as the United States' "protecting power" in Afghanistan.
"Let me again say how grateful we are for your leadership, your support on Afghanistan, but also to note that our partnership is much broader than that," Blinken told Foreign Minister Sheikh Mohammed bin Abdulrahman Al Thani.
Qatar will also assume responsibility for the security and protection of now-vacant US diplomatic facilities in the Afghan capital Kabul.
The US has numerous protecting power agreements in countries where it does not have diplomatic representation. Those notably include Switzerland in Iran, Sweden in North Korea and the Czech Republic in Syria.
Qatar, home to a major US military base, has played a major role both in the diplomacy and the evacuations as the United States ended its 20-year war in Afghanistan.
Around half of the 124,000 Westerners and Western-allied Afghans flown out in the waning days of the US military involvement transited through Qatar.
The Qataris earlier played host to negotiations between the United States and Taliban that led to the February 2020 agreement for the United States to withdraw troops.
Since the Taliban takeover, US embassy operations in Kabul have been relocated to Qatar.
US officials cautiously optimistic
The United States closed down its embassy in Kabul, which was one of its largest in the world, in August as it became clear that the Western-backed government was falling, with diplomats destroying sensitive materials and taking down the flag.
Despite the Taliban's draconian 1996-2001 regime and years of war with the United States, US officials have been cautiously optimistic on dealing with the Taliban, saying that it is largely carrying out promises to let people leave the country.
But the United States has ruled out any immediate recognition or reopening of its embassy in Kabul, saying it is waiting to see that the Taliban makes good on other concerns including on the treatment of women and prohibiting Al Qaeda from basing operations in Afghanistan.