The Russian Air Force could soon engage Ukraine at a higher level, a former F-22 fighter pilot told Fox News on Tuesday.

"I think over the next 72 hours, we're going to see a fundamentally different picture for the Ukrainian Air Force, and I'd expect to see more high-level engagement by the Russian Air Force," Dan Robinson, a Royal Air Force veteran and former F-22 fighter pilot, said Tuesday evening. 

Overnight, Russia launched the largest air assault of the invasion so far, according to Florida Sen. Marco Rubio. Wednesday marked the seventh day of the invasion.

Destruction in Ukraine after Russia's invasion

Several buildings in Starobilsk within the Luhansk Oblast region of Ukraine show significant damage because of shelling, according to images shared by the State Emergency Service of Ukraine. (State Emergency Service of Ukraine)

Russian forces have increased their attacks on Ukraine's crowded urban areas, including bombing a TV tower in the capital of Kyiv and continued shelling in Kharkiv.

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However, the airspace over Ukraine is still contested and Ukrainian air and missile systems remain "viable and intact," a senior U.S. Defense Department official said Tuesday.

Ukrainian President Zelenskyy

Ukrainian President Volodymyr Zelenskyy, center, inspects weapons during a visit to Ukrainian coast guards in Mariupol, Donetsk region, eastern Ukraine, on Feb. 17, 2022.  (Ukrainian Presidential Press Office via AP)

"The big thing is, though, what is to come? You have to wonder whether the Russian Air Force will emerge over time," Robinson told Fox News. "That's the real question."

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"As to why they haven't emerged so far, there's speculation around the actual capability of the Russian Air Force versus the perceived capability of what they have," Robinson said. 

Vladimir President Vladimir Putin

Vladimir President Vladimir Putin ordered Russia’s all-out invasion of Ukraine only eight months after TIME magazine billed President Biden as ready to take on the Russian leader.  (Sputnik, Kremlin Pool Photo via AP)

"There's speculation around a lack of sophisticated precision-guided munitions and targeting pods, which allows a certain degree of standoff and to preserve range," he continued. "Without those, they have to get up close and personal, which drags them to within range of things like Stinger missiles that Ukrainian soldiers can operate on the ground."

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Robinson said implementing a no-fly zone above Ukraine would lead to direct conflict between NATO and Russian pilots. 

"That is extremely problematic in terms of the escalatory nature of what is what this potentially could be," he told Fox News.

President Biden has said U.S. forces will not be used inside Ukraine, and there is no consideration for a no-fly zone.