Ukrainian President Volodymyr Zelenskyy embarked on a diplomatic sweep of NATO capitals ahead of a summit next week as the embattled leader seeks a path into the military alliance.

Zelenskyy landed in the Czech Republic, a staunch ally of Kyiv, for talks with his counterpart Petr Pavel, government officials and lawmakers to discuss defense support for Kyiv and integration into the European Union and NATO. He will also travel to Bratislava, the capital of Slovakia, local media reported, citing people familiar with the matter.

The Ukrainian also was set to meet meet Turkish President Recep Tayyip Erdogan in Istanbul Friday, according to officials, who spoke on condition of anonymity ahead of an announcement. Earlier, Zelenskyy made a stop in Bulgaria, where the Balkan nation’s new government has ratcheted up support for his war effort.

“The greater our political unity is, particularly in the area of European and Euro-Atlantic integration, the more the Russian dictator’s entourage will fall apart and the weaker he will become,” Zelenskyy said in Sofia. “Vilnius is now one of the key stages. Ukraine is choosing the alliance, NATO’s door is open, so it is time for an invitation to enter.“ Leaders of NATO preparing for the July 11-12 summit in Vilnius, Lithuania, are trying to strike a balance — drawing Ukraine closer without offering membership yet to a nation in the midst of a war to fend off Russia’s invasion. Zelenskyy seeks a clear path for Ukraine to join NATO after the war.

Even though NATO states have reached a consensus not to admit Ukraine in wartime, many leaders want to provide Zelenskyy with commitments that go beyond the alliance’s landmark pledge from 2008 — that Ukraine will join one day. The swing through Europe comes at a crucial time for Zelenskyy’s military effort, as Ukraine presses forward a slow-moving counteroffensive to retake territory. Both sides are engaged in intense fighting along the front line in Ukraine’s east and south. At the same time, nuclear worries have spiked as Kyiv and Moscow trade accusations of a potential attack on a Russian-occupied nuclear plant.

In Bulgaria, a new government led by the country’s two main rival parties has taken a strong line AFP/Getty Images/TNS) in cooperating with Kyiv, including increased military assistance and the sale of nuclear equipment. The parliament in Sofia approved a plan to accelerate the replenishment of state weapons and ammunition reserves, paving the way for large-scale deliveries of badly needed Soviet-era ammunition to Ukraine.

Zelenskyy was scheduled to meet Erdogan as the expiration date of the Black Sea grain deal approaches. The deal, vital in enabling Ukraine to export agricultural commodities by sea despite the invasion, is set to expire on July 17. Russia recently said it sees “no grounds for further continuation” of the agreement.

Turkey helped broker the original deal last year and wants it to be extended. Its termination could push up global food prices, given Ukraine’s importance as an exporter of grains.

Zelenskyy’s foray wasn’t always cordial. He had an encounter with Bulgarian President Rumen Radev, who has long opposed providing military aid — and who said his duty is to protect his nation in a time of regional conflict, reiterating calls for a peaceful resolution.

“The Bulgarian people realize that this is not a conflict, it’s a war,” Zelenskyy retorted.

——— (Daniel Hornak and Peter Laca contributed to this story.)