Members of the world's most powerful military bloc offered the prospect of long-term protection a day after Ukrainian President Volodymyr Zelenskiy decried as "absurd" a refusal to offer an invitation or timetable for Ukraine's entry into NATO.
Ukraine has been pushing for rapid membership while fighting a Russian invasion unleashed in February 2022 that has killed tens of thousands of people and displaced millions.
Instead, a declaration by the G7 group of the world's most industrialised countries launched a framework for bilateral negotiations to provide military and financial support, intelligence sharing and a promise of immediate steps if Russia should attack again.
"Our support will last long into the future. It's a powerful statement of our commitment to Ukraine," US President Joe Biden said alongside Zelenskiy and leaders of the G7, which is made up of the US, United Kingdom, Canada, France, Germany, Italy and Japan.
"We're going to be there as long as that takes."
Swallowing his disappointment over the lack of a membership timetable, Zelenskiy called the outcome a "meaningful success" following a flurry of announcements of military aid for Kyiv.
"Today there are security guarantees for Ukraine on the way to NATO," he said.
"The Ukraine delegation is bringing home a significant security victory for Ukraine."
Nevertheless, Zelenskiy pressed for more and said he would raise Ukraine's need for long-range weapons at a meeting with Biden at the summit.
"We can state that the results of the summit are good but if there was an invitation, they would be ideal," he added.
At a bilateral meeting, Biden promised Zelenskiy the United States was doing everything it could to meet Ukraine's needs and acknowledged Zelenskiy's frustration about the scale and speed at which he was receiving support.
"Your resilience and your resolve has been a model for the whole world to see," Biden said.
"I look forward to the day when we're having the meeting celebrating your official, official membership in NATO."
"The bad news for you is, we're not going anywhere. You're stuck with us," Biden joked, prompting laughter from Zelenskiy.
Asked by a reporter how soon after the war he would like Ukraine to join NATO, Biden responded "an hour and 20 minutes".
US national security adviser Jake Sullivan said Biden would offer Zelenskiy long-range missiles when they met.
Zelenskiy told Biden he wanted to thank "all Americans" for the billions of dollars in aid his country had received.
"You have to know that you spend this money" for more than just fighting, he said.
"You spend this money for our lives."
UK Defence Secretary Ben Wallace said he had told Ukraine that its international allies were "not Amazon" and officials in Kyiv needed to show gratitude for weapons donations to persuade foreign politicians to give more.
Zelenskiy said: "We were always grateful to the UK, prime ministers and the minister of defence because the people are always supporting us."
The UK, France, Germany and the US have been negotiating with Ukraine for weeks over a broad international framework of support, encompassing modern advanced military equipment such as fighter jets, training, intelligence-sharing and cyberdefence.
In return Ukraine would pledge better governance, including through judicial and economic reforms and enhanced transparency.
The first sitting of a new NATO-Ukraine Council was also held on Wednesday, a new format designed to tighten co-operation between Ukraine and the 31-member alliance.
NATO is built around mutual security guarantees whereby an attack on one is an attack on all, and it has carefully avoided extending any firm military commitments to Ukraine, worried it would risk taking it closer to a full-on war with Russia.
