The United States has asked United Nations Secretary-General Antonio Guterres to come up with an exit strategy for the UN's mission in Kosovo after a nearly two-decade presence there.
Haley urged Guterres to "initiate a strategic review of UNMIK to develop an exit strategy," according to a letter dated October 9, a copy of which was obtained by AFP.
The UN mission was established in 1999 as an interim administration in Kosovo following the 1998-1999 war between Serbian forces and pro-independence ethnic Albanians.
At the outset, the mission had broad powers over the territory, but following Kosovo's 2008 independence, the UN presence was scaled back.
With a civilian staff of about 300 and a dozen military liaison officers and police, UNMIK is now tasked with promoting security, stability and respect for human rights.
Haley wrote that the UNMIK review "will provide the UN Security Council information to assess and evaluate the UN presence in Kosovo" and help "advance the normalization of relations" between Serbia and Kosovo.
Last week, Haley announced that she will be stepping down as US ambassador in January.
UN spokesman Stephane Dujarric said Guterres "had received the letter and is looking at it."
Any decision to shut down the mission would have to be taken by the Security Council, which has the authority to establish and end UN operations.
Russia, one of the five veto powers on the council, has kept Kosovo under close scrutiny, often expressing concerns for the plight of minority Serbs.
The United States, by far the largest financial contributor to UN peacekeeping, is pushing for measures to streamline missions and cuts to the $6.9 billion annual budget.
The United Nations has 96,000 peacekeepers serving in 14 missions worldwide.