Ukrainian officials express frustration at the pace of weapons deliveries.

President Volodymyr Zelensky of Ukraine says he has asked NATO’s secretary general to help “overcome the reluctance” of some Ukrainian allies to provide long-range weapons and more modern aircraft and artillery.

“Delay with appropriate decisions is time lost for peace and the lives of our soldiers, who have not yet received the vitally necessary number of defense means,” Mr. Zelensky said during a joint news conference with the alliance’s secretary general, Jens Stoltenberg, in Kyiv on Thursday.

Mr. Zelensky has repeatedly expressed frustration with the pace of weapons deliveries from Western allies. He spoke on the eve of a meeting of defense and military officials from more than 40 countries supporting Ukraine in the war against Russia, a gathering known as the Ukraine Defense Contact Group.

U.S. Defense Secretary Lloyd J. Austin III told the gathering on Friday that the members of the group had together provided more than $55 billion in security assistance to Ukraine.

“Our support has not wavered,” Mr. Austin said. “And I’m proud of the progress that we have made together.”

Ukraine’s prosecutor general, Andriy Kostin, emphasized the urgency of new weapons deliveries this week during a visit to the United States, where he testified at a House panel’s hearing on Russian wartime atrocities. Appearing on CNN on Wednesday evening, Mr. Kostin pushed back on the idea that Ukraine had what it needed on the battlefield.

“I don’t think that anyone in Ukraine can say that we’re receiving everything we need,” Mr. Kostin said, adding, “We need more and we need it quicker.”

Before Friday’s meeting of the contact group, several nations announced new aid packages for Ukraine.

Denmark and the Netherlands said on Thursday that they would buy 14 Leopard 2 tanks for Ukraine, to be delivered next year.

Estonia also said it would provide 155-millimeter artillery shells, which Ukraine says it desperately needs, as part of a European Union effort to deliver more munitions. The $325 million weapons package the United States announced on Wednesday will include more than nine million rounds of small-arms munitions, as well as antitank mines.

Mr. Stoltenberg said during his visit to Kyiv that “Ukraine’s rightful place is in NATO, and over time, our support will help you make this possible.” But the alliance has not offered Ukraine a pathway to membership, and some member states have said that doing so now would further provoke Russia.

Germany’s defense minister, Boris Pistorius, said on Thursday that it was too soon to discuss Ukraine’s NATO membership.

“The door is open a crack, but this is not the time to decide this,” he said on the German channel ZDF. “First you have to fend off this conflict, this attack, and then you have to weigh this step carefully.”

NATO members have been divided over giving Ukraine a path to joining the alliance, with Central and Eastern European officials pushing for one and the United States, France and Germany resisting. Mr. Stoltenberg said in February that Ukraine would become a member, but called it a “long-term” project.