BRUSSELS (AP) — NATO Secretary-General Jens Stoltenberg on Friday pressed member countries to give more Patriot missile systems to Ukraine as President Volodymyr Zelenskyy repeated Kyiv’s almost daily appeals for more Western air defense equipment.

“NATO has mapped out existing capabilities across the alliance and there are systems that can be made available to Ukraine,” Stoltenberg told reporters after an online meeting of defense ministers from the 32-nation alliance, which Zelenskyy took part in remotely.

Russia’s air force is vastly more powerful than Ukraine’s, but sophisticated missile systems provided by Kyiv’s Western partners are a major threat to Russian aviation as the Kremlin’s forces slowly push forward along the around 1,000-kilometer (620-mile) front line in the war.

Kyiv is seeking at least seven Patriot batteries. Stoltenberg declined to say which NATO nations have air defense systems or how many might be available, saying that this is classified information, but he insisted that he expects the countries to make new announcements of support soon, not only Patriots.

“Allies must dig deep into their inventories and speed up the delivery of missiles, artillery and ammunition. Ukraine is using the weapons we provide it to destroy Russian combat capabilities. This makes us all safer,” he said.

“Support to Ukraine is not charity. It is an investment in our own security,” Stoltenberg added.

Patriot missile batteries can take two years to make, so countries that have them can be reluctant for security reasons to leave themselves exposed. Germany had a total of 12, but is supplying three to Ukraine. Poland, which borders Ukraine, has only two and needs them for its own defenses.

Greece, the Netherlands, Romania and Spain also possess Patriots. One major advantage of providing the U.S.-made systems, apart from their effectiveness, is that Ukrainian troops are already trained in their use.

NATO keeps track of the stocks of weapons held by its 32 member countries to ensure that they are able to execute the organization’s defense plans in times of need.

But Stoltenberg said that if dropping below the guidelines is “the only way NATO allies are able to provide Ukraine with the weapons they need to defend themself, well that’s a risk we have to take.”

Beyond providing new Patriot batteries, Stoltenberg said that it’s also important for the allies to ensure that the batteries they send are well maintained, have spare parts and plenty of interceptor missiles.