Ukraine’s air defenses play a key role in countering the Russian invasion, preventing Moscow’s forces from gaining control of the skies and helping protect the country from missile and drone attacks.

But as Russia ramps up strikes against Ukraine’s energy infrastructure as it faces mounting casualties on the ground, Kyiv is urging its supporters — particularly the United States — to deploy advanced equipment like Patriot missiles and F-15 fighter jets.

“As Ukraine continues to fight, air defense capabilities will become critical to its future success,” Gen. Mark Milley, the top US military officer, said on Wednesday.

“An integrated air and missile defense system is necessary as Ukraine repels Russian airstrikes.”

Stressing the urgency for Ukraine, the country’s military said it registered 111 Russian missile strikes and 26 kamikaze drones on Tuesday, which Milley said was “probably the largest wave of missiles we’ve seen since the war began.”

When Russia invaded in February, Ukraine’s air defenses consisted largely of Soviet-era aircraft and missile systems, which Kyiv used effectively to deny Moscow air superiority.

That has affected “almost every aspect of Russian Air Force employment,” said Karl Mueller, a senior political scientist at RAND Corporation who specializes in military and national security strategy.

Ukraine’s medium- and long-range systems have urged Russia to conduct missile strikes to sidetrack its planes — a tactic limited by Moscow’s stockpiles of such weapons, Mueller said.

And short-range systems have “really limited the Russians’ ability to deploy their attack helicopters and ground-attack aircraft over the battlefield.”

Mueller attributed the success of Ukraine’s air defenses to several factors, including that the country “had many surface-to-air missile systems” that were “competently operated.”

Ukraine’s air defenses are also almost entirely mobile, he said, helping them disperse and evade Russian attacks.

In addition, “the Russian Air Force is not that good at attacking air defense systems” as they lack the US military’s specialized units for this mission.

Ukraine’s air defenses have been significantly reinforced since the start of the war: the United States provided NASAMS and Germany with IRIS-T – two advanced systems – while older equipment such as the S-300 and HAWK systems and Stinger missiles were also donated.

Milley said a Wednesday meeting of dozens of Ukrainian supporters “focused on how we, as a global coalition, can provide Ukraine with the right mix of air defense systems and munitions to continue their control of the skies and prevent the Russians from gaining air superiority.” “

Kiev’s forces have successfully shot down Russian missiles and drones and shot down 102 air targets since November 11, according to the military.

But no air defense system can block all attacks – as demonstrated by the strikes that cut power from millions on Tuesday – and Ukraine is looking for additional help.

Foreign Minister Dmytro Kuleba said on Twitter on Thursday that he was “convinced the time has come for ‘patriots'” after asking for F-15 and F-16 fighter jets earlier in the week.

Concerns that Patriot missiles or Western jets could be viewed as an escalation by Russia is a factor that likely contributed to the reluctance to provide such items, given the time it takes to train Ukrainian forces in their use , another is.

But “in the long term, Ukrainians will need Western-made aircraft,” Mueller said.

As Moscow’s strike campaign continues, beefing up Ukraine’s air defenses is “clearly … a top priority in terms of helping Ukrainians survive against Russian attacks,” he said.