His letter calls for a conference facilitated by the United Nations.

Blinken also made clear in the letter that the Biden administration continues to consider a full withdrawal of the roughly 2,500 U.S. forces in the country by the May 1 deadline negotiated by Trump administration.
The State Department declined to comment on the TOLONews report.
We have not made any decisions about our force posture in Afghanistan after May 1, the State Department said in a statement. All options remain on the table.
Afghanistan presents one of the new administrations most difficult foreign policy decisions. The U.S. public is weary of a war nearly 20 years old, but pulling out now could be seen as giving the Taliban too much leverage and casting a shadow over the sacrifices made by U.S. and coalition troops and Afghan civilians.
Blinken urged Ghani to quickly embrace the proposal and underscored his concern that the security situation in the country could quickly deteriorate as the weather warms in Afghanistan
Even with the continuation of financial assistance from the United States to your forces after an American military withdrawal, I am concerned that the security situation will worsen and the Taliban could make rapid territorial gains, Blinken wrote in the letter.