VILNIUS, Lithuania — NATO leaders said Tuesday that they would allow Ukraine to join the alliance “when allies agree and conditions are met” — a pronouncement that came just hours after President Volodymyr Zelenskyy blasted the organization’s failure to set a timetable for his country as “absurd.”

Instead, alliance leaders decided to remove obstacles to Ukraine’s membership path so that it can join more quickly once the war with Russia is over.

“We reaffirmed Ukraine will become a member of NATO and agreed to remove the requirement for a membership action plan,” NATO Secretary-General Jens Stoltenberg told reporters, referring to a key step in the process that involves advice and assistance for countries seeking to join.

“This will change Ukraine’s membership path from a two-step path to a one-step path,” Stoltenberg said.

Although many NATO members have funneled arms and ammunition to Zelenskyy’s forces, there is no consensus among the 31 allies for admitting Ukraine into NATO’s ranks.

Zelenskyy pushed back sharply against the decision as he headed to the annual NATO summit in Vilnius.

“It’s unprecedented and absurd when a time frame is set neither for the invitation nor for Ukraine’s membership,” Zelenskyy tweeted. “While at the same time, vague wording about ‘conditions’ is added even for inviting Ukraine. It seems there is no readiness to invite Ukraine to NATO or to make it a member of the Alliance.”

NATO membership would afford Ukraine protection against a giant neighbor that annexed its Crimean Peninsula almost a decade ago and more recently seized vast swaths of land in the east and south. Joining NATO would also oblige Kyiv to reform its security institutions, improve governance and curb corruption — work that would also ease the country’s path into the European Union.

Asked about Zelenskyy’s concerns, Stoltenberg said the most important thing now is to ensure that his country wins the war, because “unless Ukraine prevails there is no membership to be discussed at all.”

The broadside from Zelenskyy could renew tensions at the summit shortly after it saw a burst of goodwill following an agreement by Turkey to advance Sweden’s bid to join NATO. Allies hope to resolve the seesawing negotiations and create a clear plan for the alliance and its support for Ukraine.

The Ukrainian president, who was to meet Wednesday with U.S. President Joe Biden and other NATO leaders, expressed deep frustration in an emotional speech in downtown Vilnius.

“Today I started my journey with faith in solutions, with faith in strong partners, with faith in NATO … in a NATO that does not hesitate, that does not waste time and does not look over their backs at any aggressor,” Zelenskyy said.

“I would like this faith to become confidence, confidence in the decisions that we deserve, all of us — every soldier, every citizen, every mother, every child,” he said. “Is that too much to ask?”

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

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 urged caution. Biden said last week that Ukraine was not 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 to aggression.

Concretely, NATO leaders decided to launch a series of multiyear programs to bring Ukraine’s Soviet-era military equipment and doctrines up to modern standards so the country can operate fully with the alliance.

On Wednesday, the leaders and Zelenskyy are set to launch a new, upgraded forum for their cooperation: a NATO-Ukraine Council, where all parties can convene crisis talks if their security is threatened.

To fast-track its future membership, the leaders agreed to do away with a membership action plan for Ukraine. The plan involves a tailor-made package of advice and assistance for countries preparing to join NATO. Bosnia is now taking part in one.

Pressed by reporters to say what kind of conditions are being placed on Ukraine joining, Stoltenberg said: “We want modern defense and security institutions.”

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.

Turkish President Recep Tayyip Erdogan will ask his parliament to approve Sweden joining NATO. Hungarian Prime Minister Viktor Orban, another holdout, is set to take a similar step on Sweden.

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

After the NATO summit ends Wednesday, Biden will travel to Helsinki. On Thursday, he will celebrate Finland’s recent entry into NATO.