On Tuesday, Zelensky said it was "unprecedented and absurd" that a timeframe was set "neither for the invitation nor for Ukraine's membership."
Later in the day, during the dinner on the sidelines of the NATO summit, Zelensky was told that he had gone too far and advised to look at the full package of NATO commitments to Kiev, a person present at the dinner was cited as saying by US media.
It was further reported that the US delegation was "irritated" by Zelensky's comments as UK representatives were looking for ways to alleviate tensions. As for German officials, they were allegedly trying to find alternatives to resolve the situation.
The Wednesday revelation come as earlier reports cited UK Defense Secretary Ben Wallace as doubling down on the sentiment. "Whether we like it or not, people want to see gratitude," the official said before pointing out that nations were "giving up their stock" of weapons to Ukraine.
In early June, Zelensky said that Kiev hoped to receive a clear invitation to join the bloc at the Vilnius summit. He also said Kiev was disappointed it had not yet received a clear positive response about joining both the European Union and NATO.