BRUSSELS (AP) — NATO defense ministers met Wednesday as its member countries face the twin challenges of struggling to make and supply weapons to Ukraine while protecting vital European infrastructure like pipelines or cables that Russia might want to sabotage in retaliation.

In the almost eight months since Russian President Vladimir Putin ordered his troops into Ukraine, the 30-nation alliance has trod a fine line as an organization, providing only non-lethal support and defending its own territory to avoid being dragged into a wider war with a nuclear-armed Russia.

Individual allies, however, continue to pour in weapons and ammunition to Ukraine, including armored vehicles and air defense or anti-tank systems. They're also training Ukrainian troops.

But as the Russian missile strikes across Ukraine this week demonstrated, this is not enough. NATO defense ministers have been taking stock of the supply effort so far and debating ways to encourage the defense industry to quickly ramp up production.

"Allies have provided air defense, but we need even more. We need different types of air defense, short-range, long-range air defense systems to take (out) ballistic missiles, cruise missiles, drones, different systems for different tasks," NATO Secretary-General Jens Stoltenberg said.

"Ukraine is a big country, many cities. So we need to scale up to be able to help Ukraine defend even more cities and more territory against horrific Russian attacks," Stoltenberg told reporters ahead of the meeting at NATO headquarters.

After a separate gathering of the Ukraine Contact Group — 50 nations that meet to assess Ukraine's needs and drum up equipment — U.S. Gen. Mark Milley, chairman of the Joint Chiefs of Staff, said that Ukraine wants a complete air defense system to defend against aerial attack.

"What Ukraine is asking for, and what we think can be provided, is an integrated air missile defense system. So that doesn't control all the airspace over Ukraine, but they're designed to control priority targets that Ukraine needs to protect," Milley told reporters.

It would involve short-, medium- and long-range systems capable of firing projectiles at all altitudes.

"It's a mix of all these that deny the airspace to Russian aircraft" and missiles, Milley said. "They're trying to create a defensive system."

At the same time, national military stocks are being depleted. Some countries are growing reluctant to provide Ukraine with more when they are no longer entirely sure they can protect their own territories and airspace.

The conundrum for the allies is to find a way to arm Ukraine without disarming themselves.

For the defense industry, companies need long-term orders and certainty before they commit to extending production lines. But no one is sure how long the war in Ukraine will last, making it difficult to know how much equipment is needed.

So the United States and its partners want to boost weapons production by sending clear signals to industry, as they pool resources and send Ukraine the hardware that it needs, all while ensuring that no major gaps appear in national stockpiles.

Putin, for his part, has warned NATO against deeper involvement in Ukraine. In recent weeks, as power and gas bills spiral and Europe struggles to decrease its dependency on Russia for energy, apparent sabotage damaged two major pipelines once meant to bring Russian natural gas to Germany.

The Polish operator of the Druzhba — or "Friendship" — oil pipeline, one of the world's longest and which originates in Russia, said Wednesday that it had detected a leak underground near the city of Plock in central Poland. The line supplies crude to Belarus, Ukraine, Poland, Austria and Germany.

In response to the incidents, Stoltenberg said, NATO has "doubled our presence in the Baltic and North Seas to over 30 ships, supported by maritime patrol aircraft and undersea capabilities."

It's small comfort, given that about 8,000 kilometers (nearly 5,000 miles) of oil and gas pipelines crisscross the North Sea alone. Even the resources of international energy companies, national authorities and NATO may not be enough to protect them.

NATO's aim, for now, is to better coordinate between these actors, to better gather intelligence and improve the way it is shared, and watch over facilities, with aerial and undersea drones and other surveillance equipment.

No responsibility has been established for the pipeline incidents. But NATO is also trying to be clear in deterring Russia. "Any deliberate attack against allies' critical infrastructure would be met with a united and determined response," Stoltenberg said.

He declined to say what kind of response that might be.

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