Ukraine has gone on the offensive in its push to join the NATO defence alliance and obtain more weapons for its fight against Russia's all-out invasion.
Ukrainian President Volodymyr Zelenskiy told US broadcaster ABC News that he wants "all the decisions to be made during the summit" not ahead of time.
"I don't want to go to Vilnius for fun if the decision has been made beforehand," he said on Sunday.
The two-day NATO summit begins in Vilnius, the Lithuanian capital on Tuesday and will focus, in part, on how to bring Ukraine, which is under attack from Russia, closer to the alliance and what security guarantees it can be given after Russia's war of aggression ends.
"Ukraine should get clear security guarantees while it is not in NATO," Zelenskiy told ABC. "And this is a very important point. Only under these conditions would our meeting make sense."
However US President Joe Biden cast doubt on Ukraine being offered NATO membership.
"I don't think it's ready for membership in NATO," Biden told CNN in an interview aired on Sunday.
Biden said he hoped that NATO leaders would "lay out a rational path for Ukraine to be able to qualify to be able to get into NATO."
He said that in order to join the military alliance countries must "meet all the qualifications, from democratisation to a whole range of other issues." He added that bringing Ukraine into the alliance now would mean "war with Russia."
John Kirby, the communications director for the US National Security Council, said NATO is ready to provide security guarantees but not immediate membership.
At the summit, observers will see that the allies have "a concerted unified approach to making it clear that NATO is eventually going to be in Ukraine's future," and before that they will "continue to help Ukraine defend itself," he said.
Kirby noted that Ukraine still has "to work on some reforms, political reforms in the country. And of course, there's still a war right now."
"So I think we've got to focus on making sure they can succeed right now and give them the time and space to continue to work on the reforms that are necessary for any NATO ally."
with Reuters