Ukraine will be told it is currently too corrupt to join Nato, in a major blow to Volodymyr Zelensky.
The alliance will request “additional steps” from Kyiv before membership talks progress, a senior official in the US State Department said.
The position will be set out in writing in the Nato communique to be signed at the alliance’s annual summit on July 9.
“We have to step back and applaud everything that Ukraine has done in the name of reforms over the last two-plus years,” the official told The Telegraph.
“As they continue to make those reforms, we want to commend them, we want to talk about additional steps that need to be taken, particularly in the area of anti-corruption. It is a priority for many of us around the table,” the source added.
Mr Zelensky, Ukraine’s president, is pushing for swift Nato membership after the war ends to protect from future invasion. It would compel the US and Europe to come to the defence of Kyiv in the event of any Russian attack.
But corruption has been a sticking point in recent talks between Nato member states over whether to offer Ukraine a concrete timetable for joining the Western military alliance.
The Telegraph recently revealed that the US is blocking British and European efforts to put in writing an “irreversible” path towards Nato membership for Ukraine.
Ukraine has suffered from corruption, particularly in its armed forces, since the dissolution of the Soviet Union.
Mr Zelensky has sacked military chiefs as part of an effort to curb the problem, especially in the area of defence procurement.
Joe Biden raised “significant corruption” in an interview with Time magazine this year, during which he ruled out supporting the “Nato-isation of Ukraine”.
Nato diplomats and officials have given Ukraine a list of reforms it will be expected to carry out before its membership ambitions can be realised, a US defence official said.
“That’s something Nato has been doing quietly under the radar that helps them get closer to membership,” the source added.
By Joe Barnes