U.S. President Joe Biden on Tuesday hailed an agreement for Sweden to join NATO as more work remained to determine a path forward for Ukraine's future with the alliance.
Ukrainian President Volodymyr Zelenskyy criticized the absence of a timetable for his country's entry as "absurd."
Biden described the summit in Vilnius, Lithuania, as a "historic moment" and said the United States agreed with a proposal, yet to be released publicly, to outline a path for Ukraine's eventual membership.
However, Zelenskyy, who was on his way to Vilnius to join the summit, expressed disappointment with how the negotiations were playing out.
"We value our allies," he wrote on Twitter 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."
A public flash of anger from the Ukrainian leader, who has been hailed by the West as a hero for his leadership during the Russian invasion, could renew tensions in Vilnius just as they had begun to subside.
On Monday evening, the night before the summit opened, Turkey withdrew its objections to Sweden joining the alliance, a step toward the unity that Western leaders have been eager to demonstrate in the face of Russia's invasion of Ukraine.
The deal was reached after days of intensive meetings, and it's poised to expand the alliance's strength in Northern Europe.
Biden, Zelenskyy expected to meet during this week's NATO summit
The meeting of leaders is expected to focus on ongoing U.S. support for Ukraine's war with Russia.
"Rumors of the death of NATO's unity were greatly exaggerated," Jake Sullivan, the U.S. national security adviser, 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.
The outcome is a victory 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 began Tuesday by meeting with Lithuanian President Gitanas Nauseda, where he emphasized his commitment to transatlantic cooperation.
"Nothing happens here that doesn't affect us," he 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.
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.
NATO members are now focused on Ukraine's desire to join NATO. The Baltic states — including Lithuania, which is hosting the event — have pushed for a strong show of support and a clear pathway toward membership for Ukraine.
The United States and Germany have resisted that, and 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.
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."
Zelenskyy is scheduled to attend the summit on Wednesday and meet with Biden.
NATO committed to eventual membership for Ukraine in 2008 under President George W. Bush, a goal Stoltenberg reiterated in Vilnius.
He said NATO had agreed to forgo requiring a "membership action plan" for Ukraine, but was not more specific.
"Ukraine is much closer to NATO so I think the time has come to reflect that in other NATO decisions," Stoltenberg said.
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."
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.
After the summit ends on Wednesday, Biden will travel to Helsinki to celebrate Finland's recent entry into NATO and meet with Nordic leaders.
