Western intelligence says Russia is amassing aircraft on Ukraine's border, as countries look to the skies to break deadlock

• Russia is gathering air power at Ukraine's border, according to unnamed Western officials.
• US defense secretary Lloyd Austin denied this, but called on the West to rush air defenses to Ukraine.

Western officials are warning of an accumulation of Russian aircraft on Ukraine's borders, potentially signaling a major air offensive as the invasion approaches its one-year anniversary, according to multiple reports.

NATO allies have noted both fixed-wing and rotary aircraft as part of the build-up, unnamed Western officials told the Financial Times.

An unnamed senior US official echoed the assessment, telling Politico that there is "some prepositioning of air assets" as part of wider arrangements for a new mobilization.

The reports come as Ukraine's allies embark on a renewed rush to bring air defenses to the country.

During a summit this week between NATO defense ministers in Brussels, US Defense Secretary Lloyd Austin spoke of Russia's considerable air capabilities and the urgent need to bring air defenses to Ukraine.

He denied that the Pentagon was seeing evidence of Russian preparations for a "massive aerial attack." But, he added, "Russia has a substantial number of aircraft in its inventory and a lot of capability left."

He said that "we need to do everything that we can" to bring air defenses to Ukraine.

NATO Secretary General Jens Stoltenberg reaffirmed the bloc's commitment to protect Ukraine "for as long as it takes."

There are growing signs that a long-anticipated renewed Russian offensive — which reached an effective stalemate on the ground — has begun. Stoltenberg remarked on Monday: "We're seeing the start already."

The US is expected to announce another major aid package for Ukraine in the coming days, Sky News reported.

Despite repeated pleas from Ukraine, Western allies have long balked at providing fighter jets, both on the basis of their extensive training requirements and ongoing concerns about the potential provocation in sending offensive, rather than defensive gear.

Russia ceased committing large parts of its piloted air force to its invasion of Ukraine after an early push, as NPR reported. As of late last year, the bulk of its aerial losses — around 300 — were small, relatively cheap drones, as Forbes reported.

Russia has also primarily kept its modern Sukhoi Su-57 combat jet operations within its own airspace, over fears that they will be shot down, per UK intelligence.

Justin Bronk, an airpower and technology expert with the Royal United Services Institute (RUSI) think tank in London, told Insider in January that Russia fears Ukraine's NATO allies could learn from the technology of any downed jet.

But facing the full force of Russia's advanced fighter jets is a major concern for Ukraine, with its air force far outmatched, as Insider reported.