Let's get a little more now on President Zelensky's strongly-worded statement.
He says, without a timeframe on Ukraine being invited to join Nato, "a window of opportunity is being left to bargain Ukraine's membership in Nato in negotiations with Russia".
"And for Russia, this means motivation to continue its terror."
Kyiv has conceded that Ukraine wouldn't be able to join Nato while the war with Russia is ongoing - but it is pushing for a clear timeline.
Zelensky says 'absurd' if no timetable given for Ukraine's Nato bid
Ukraine's President Volodymyr Zelensky has hit out at Nato, saying it's "absurd" that a timeframe is not being set for Ukraine to be invited to join the military alliance.
"It’s unprecedented and absurd when timeframe is not set neither for the invitation nor for Ukraine's membership," he wrote in a strongly-worded statement on Twitter
"It seems there is no readiness neither to invite Ukraine to Nato nor to make it a member of the alliance."
Nato agreed in 2008 that Ukraine "will" become a member. But the alliance did not say how and when this might happen.
"Now, on the way to Vilnius, we received signals that certain wording is being discussed without Ukraine," he adds.
He emphasises that this wording is about "the invitation to become Nato member, not about Ukraine's membership".
"Uncertainty is weakness. And I will openly discuss this at the summit," he says.
Say cheese! It's family photo time
As is traditional at these events, Nato leaders all stood together to take a so-called family photo.
We didn't manage to get ourselves a body language interpreter for the occasion - we'll leave all that fun to you:
