Nato leaders grapple with Ukraine’s membership ambitions at their summit on Tuesday, their determination to face down Russia boosted by a breakthrough in Sweden’s bid to join the alliance.

German Patriot missile systems and French fighter jets were guarding the skies as Nato leaders gathered in Lithuania, on land once occupied by Moscow on the alliance’s eastern flank.

Ukrainian President Volodymyr Zelensky will head to Vilnius for the two-day summit to make the case that Kyiv has earned the right to join when the Kremlin’s invasion ends.

“Ukraine deserves to be in the alliance. Not now, because now there’s war, but we need a clear signal,” Zelensky said in Kyiv.

The Western military alliance is set to offer its full-throated backing for Kyiv’s quest for victory, but its 31 nations are divided over how far to go on letting Ukraine join their ranks.

While Ukraine’s neighbours have pushed for an explicit timetable, heavyweights the United States and Germany are reluctant to go beyond an earlier vow that it will become a member one day.

US President Joe Biden, who will meet with Zelensky on Wednesday, has said there is no agreement to offer Kyiv membership while its war with Russia rages, as this would drag Nato directly into the conflict.

White House National Security Adviser Jake Sullivan told reporters Nato will draw up a path of reforms that Ukraine will need to undertake in order to eventually join, but without giving a “timetable”.

The alliance is offering Kyiv a branch by simplifying its eventual accession bid and dropping a requirement that it completes a formal road map of reforms.

As Ukraine wages a punishing counter-offensive, dominant powers the United States, Britain, France and Germany have been negotiating long-term commitments on weapons supplies with Kyiv.

These fall far short of Zelensky’s desire to be under Nato’s collective defence umbrella but could reassure him that his nation can keep on fighting.

Drawing up something similar to the US arrangement with Israel — which sees Washington sending $3.8 billion (3.5 billion euros) of weapons each year for a decade — is one possibility.

Lithuania’s President Gitanas Nauseda insisted only Nato’s article five mutual defence clause “can provide real security guarantees which would deter Russia from any future aggression.”

In a reminder of the daily threat facing Ukrainians, Russia targeted Kyiv and the port city of Odesa in yet another overnight drone attack. There was no immediate information on casualties.

Nato overhaul

The biggest war in Europe since World War II has propelled Nato into the most sweeping overhaul of its defences since the end of the Cold War.

Alliance leaders should sign off on new regional plans to protect against any potential Russian attack and agree to bolster defence spending targets.

“On our side of the fence, we have to up the game of preparedness and just keep our eyes open,” Latvian Prime Minister Krisjanis Karins said.

But letting Ukraine in remains a step too far for some for now.

Diplomats have been wrangling up to the wire over the exact wording of the final communique as they seek to convince Ukraine it is moving forward.

“I’m confident it will be a positive and strong message on Ukraine and the path forward for membership,” Nato chief Jens Stoltenberg said.

In 2008, Nato left Ukraine in a grey zone by vowing it will become a member but failing to back that up with any concrete progress.

Kyiv’s push to join the Western bloc enraged Putin and was used as a pretext by the Kremlin leader to justify his war.

Turkey backs Sweden

But more than 500 days into the conflict, Putin is facing a greater Nato presence lined up against Russia.

After hours of talks, Turkish President Recep Tayyip Erdogan on Monday ended months of deadlock by agreeing to forward Sweden’s application for Nato membership to his parliament for approval.

Stoltenberg hailed a “historic day” that should help clear the way for Sweden to become the second new member since Finland joined in April.

Turkey has been holding up Sweden’s application to join the Atlantic alliance, accusing Stockholm of harbouring Kurdish activists Ankara regards as terrorists.

Erdogan upped the stakes further, demanding that the European Union revive Turkey’s stalled EU membership bid as a precondition for Sweden joining Nato.

In a joint statement, Stockholm said it will now “actively support” efforts to reinvigorate Turkey’s long-stalled accession bid for the EU.

Hungary is also yet to approve it, although Prime Minister Viktor Orban’s government has vowed it will not be the last to make the step, implying it will move soon.