Zelensky pushes for E.U. and NATO membership at a meeting of European leaders in Moldova.

NATO should decide this year whether to admit Ukraine as a member, President Volodymyr Zelensky of Ukraine said on Thursday, intensifying his case, at a summit of European leaders in Moldova, for the country’s accession to the alliance.

Russia’s invasion of Ukraine more than 15 months ago has given added urgency to the country’s application in September to join NATO, a body set to hold a summit meeting in the Lithuanian capital, Vilnius, next month.

The government in Kyiv views membership as the ultimate guarantee of its security. The United States and other NATO allies, while supporting the government in Kyiv with billions of dollars in military aid, have so far proved reluctant to take that step given that it could bring the alliance into direct conflict with Moscow.

“This year is for decisions,” Mr. Zelensky said at the European Political Community summit at a castle outside the Moldovan capital. He spoke in English. “In summer in Vilnius at the NATO summit, a clear invitation from members of Ukraine is needed, and security guarantees on the way to NATO membership are needed.” His comments were reported by Reuters.

Few expect concrete progress at the one-day summit of 47 leaders.

But the gathering — a forum for almost all of Europe’s leaders — sought to showcase Western solidarity in defiance of the Kremlin’s calculation that political and economic fatigue would undermine support for Ukraine. Russia and its close ally, Belarus, were not invited and the newly re-elected president of Turkey, Recep Tayyip Erdogan, chose not to attend.

Kaja Kallas, the prime minister of Estonia, said the attendance of so many leaders sent “a signal that multilateralism actually works, and also that we are behind Moldova and we are behind Ukraine.” The West, she added, needed to show President Vladimir V. Putin that he cannot wait out Ukraine and the West. “As soon as Putin realizes and Russia realizes they made a mistake with the war in Ukraine, the war will be over.”

Thursday’s meeting had a loose agenda, focusing on issues such as fostering political dialogue and strengthening security, stability and prosperity, according to a description of the forum on a European Union website.

Some analysts have doubted its value, not least given disagreements within Europe on the war. But others argue that, while the European Political Community is new — the first meeting was held in October — it could provide opportunities for dialogue.

Arriving at the summit, Mr. Zelensky said that security guarantees were also important for Moldova. The war in Ukraine and its economic fallout have reverberated in the Eastern European country, which has taken in large numbers of Ukrainian refugees.

Moldova has faced growing pressure on its leadership, and this year President Maia Sandu accused Russia of trying to topple her government through protests organized by pro-Russian forces.

“I think security guarantees are very important, not only for Ukraine. For all the neighbors,” Mr. Zelensky told journalists after a meeting with Ms. Sandu. “What is very important — our future in E.U. and NATO,” he said. Ukraine took some of its first steps toward European Union membership around a decade ago.

Mr. Zelensky, who spent the first months after the invasion in Kyiv as a show of defiance, has traveled extensively in Europe in recent weeks and attended a summit of the Group of 7 leaders in Japan last month. In every forum, he has pressed his case for greater military and diplomatic support for his country.

Ukraine, however, was not the only issue being discussed at the summit.

The leaders of Armenia and Azerbaijan were also expected to meet at the summit in the latest talks focused on a long-running dispute over their common border and the Nagorno-Karabakh region. Discussions on the issues have also been held outside Washington and in Brussels in recent weeks.

Charles Michel, the European Council president, who has led negotiations, said before the summit that the two leaders had “made some progress and I hope today will be an occasion to confirm a common political will to normalize the relation between both countries,” according to a Reuters report.

Andrew Higgins contributed reporting.