Ukrainian President Volodymyr Zelenskyy on Tuesday blasted as “absurd” the absence of a timetable for his country’s membership in NATO, injecting harsh criticism into a gathering of the alliance’s leaders that was intended to showcase solidarity in the face of Russian aggression.

The broadside from Zelenskyy could renew tensions at the summit shortly after it saw a burst of goodwill after Turkey agreed to advance Sweden’s bid to join NATO. Allies hope to resolve the seesawing negotiations and leave Vilnius with a clear path forward for the alliance and its support for Ukraine.

Officials have drafted a proposal, which has not been publicly released, on Ukraine’s potential membership. U.S. President Joe Biden expressed support during a meeting with NATO Secretary-General Jens Stoltenberg, but Zelenskyy wrote on Twitter that he was not satisfied.

“We value our allies,” he said but added that “Ukraine also deserves respect.”

“It’s unprecedented and absurd when time frame is not set neither for the invitation nor for Ukraine’s membership,” Zelenskyy said. He finished with, “Uncertainty is weakness. And I will openly discuss this at the summit.”

Zelenskyy is expected to meet with Biden and other NATO leaders on Wednesday.

There have been sharp divisions within the alliance over Ukraine’s desire to join NATO, which was promised back in 2008 even though few steps were taken toward that goal.

Stoltenberg wrote in Foreign Affairs on Monday that the alliance would “upgrade our political ties” by forming a NATO-Ukraine Council, which would be “a platform for decisions and crisis consultation.”

In addition, he said Tuesday that NATO would forgo requiring “membership action plan” for Ukraine, removing another hurdle.

But that did not seem to alleviate Zelenskyy’s concerns. In addition, the Baltic states — including Lithuania, which is hosting the summit — have pushed for a strong show of support and a clear pathway toward membership for Ukraine.

However, the United States and Germany were urging caution. Biden said last week that Ukraine wasn’t ready to join. Members of NATO, he told CNN, need to “meet all the qualifications, from democratization to a whole range of other issues,” a nod toward longstanding concerns about governance and corruption in Kyiv.

In addition, some fear that bringing Ukraine into NATO would serve more as a provocation to Russia than as a deterrence against aggression.

Jake Sullivan, Biden’s national security adviser, said allies were debating the “precise nature” of Ukraine’s pathway to membership. However, he promised that the summit would demonstrate how Russian President Vladimir Putin’s hopes for fractures within NATO will be unfulfilled.

“He has been disappointed at every turn,” Sullivan said. “Vilnius will very much disappoint him.”

The dispute over Ukraine stands in contrast to a hard-fought agreement to advance Sweden’s membership. The deal was reached after days of intensive meetings, and it’s poised to expand the alliance’s strength in Northern Europe.

“Rumors of the death of NATO’s unity were greatly exaggerated,” Sullivan told reporters triumphantly on Tuesday.

According to a joint statement issued when the deal was announced, Erdogan will ask Turkey’s parliament to approve Sweden joining NATO. Hungarian Prime Minister Viktor Orban, another holdout, is expected to take a similar step. Hungary’s foreign minister said Tuesday that his country’s ratification of Sweden’s NATO membership was now just a “technical matter.” Erdogan has not yet commented publicly.

The outcome is a victory as well for Biden, as well, who has touted NATO’s expansion as an example of how Russia’s invasion of Ukraine has backfired on Moscow. Finland has already become the 31st member of the alliance, and Sweden is on deck to become the 32nd. Both Nordic countries were historically nonaligned until the war increased fears of Russian aggression.

Because of the deal on Sweden’s membership, “this summit is already historic before it has started,” Stoltenberg said.

Kremlin spokesman Dmitry Peskov told reporters that NATO’s expansion is “one of the reasons that led to the current situation.”

“It looks like the Europeans don’t understand their mistake,” Peskov said. He warned against putting Ukraine on a fast track for NATO membership.

“Potentially it’s very dangerous for the European security, it carries very big risks,” Peskov said.

Biden and Erdogan were scheduled to meet Tuesday evening, and it was unclear how some of the Turkish president’s other demands will be resolved. He has been seeking advanced American fighter jets and a path toward membership in the European Union. The White House has expressed support for both, but publicly insisted that the issues were not related to Sweden’s membership in NATO.

“I stand ready to work with President Erdogan and Turkey on enhancing defense and deterrence in the Euro-Atlantic area,” Biden said in a statement late Monday.

The phrasing was a nod to Biden’s commitment to help Turkey acquire new F-16 fighter jets, according to an administration official who was not authorized to comment publicly.

The Biden administration has backed Turkey’s desire to buy 40 new F-16s as well as modernization kits from the U.S. It’s a move some in Congress, most notably Senate Foreign Relations Committee Chairman Bob Menendez, D-N.J, have opposed over Turkey blocking NATO membership for Sweden, its human rights record and other concerns.

In Washington, Menendez said he was “continuing to have my reservations” on providing the fighter aircraft to Turkey. If the Biden administration could show that Turkey wouldn’t use the F-16s belligerently against other NATO members, particularly its neighbor Greece, and meet other conditions, “then there may be a way forward,” Menendez told reporters.

Biden is on a five-day trip to Europe, with the NATO summit as its centerpiece.

The president spent Monday in the United Kingdom, meeting at Windsor Castle with King Charles III and in London with Prime Minister Rishi Sunak.

He met Tuesday with Lithuanian President Gitanas Nauseda, emphasizing his commitment to transatlantic cooperation, before he joined the NATO gathering.

“Nothing happens here that doesn’t affect us,” Biden told Nauseda. The White House said Nauseda presented Biden with the Order of Vytautas the Great, the highest award a Lithuanian president can bestow. Biden is the first U.S. president to receive it.

After the summit ends on Wednesday, Biden will travel to Helsinki. On Thursday, he’ll celebrate Finland’s recent entry into NATO and meet with Nordic leaders.

(AP)