Ukrainian President Volodymyr Zelensky on Monday said that Kiev requires 25 Patriot air defense systems to fully safeguard its airspace, though he did not reveal the current number of Patriot systems the country possesses.

"If I say how many more we need, it will become clear how many we already have. I can tell you how many Patriots we need ... We need 25 systems to completely cover the skies over Ukraine," Zelenskyy told reporters.

Zelensky also said that Ukraine requires additional Western air defense systems beyond the US-made Patriots.

For months, Ukraine has been requesting seven additional Patriot systems to defend against Russian strikes two and a half years into the war.

NATO chief Jens Stoltenberg urged alliance members to continue their support for Kiev, warning that a Russian victory would pose the "greatest risk" to the US-led military bloc.

"The outcome of this war will shape global security for decades to come," Stoltenberg emphasized.

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On July 10, the US, Germany, Romania, and the Netherlands announced at NATO's 75th anniversary summit that they are providing Ukraine with four Patriot systems.

President Joe Biden described the "historic donation", which includes a new US Patriot system, as part of NATO's efforts to protect Ukraine from Russian air attacks.

Germany and Romania had already confirmed they were sending two Patriot systems each, while the Netherlands mentioned it was assembling one to assist Kiev. Italy is also contributing a separate missile system.

"The war will end with Ukraine remaining a free and independent country. Russia will not prevail," Biden stated at a ceremony in the same room where NATO's founding treaty was signed in 1949.

"This is a pivotal moment for Europe, for the transatlantic community, and, I might add, for the world," he added.

Biden said with other leaders that they aim to send dozens more shorter-range systems to Ukraine in the coming months.

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