Inability.

This is coolbert:

Not a fighter-bomber! Think rather strictly an interceptor aircraft or a stand-off weapons delivery system! 

Soviet/Russian MiG-31 Foxhound. Not an air superiority fighter plane.

"WARPLANES: One Fighter-Bomber Terrorizes a Nation"

As extracted from a Strategy Page article. 

"December 10, 2023: In Ukraine the government is seeking a solution to Russian use of a single fighter-bomber carrying a four-ton hypersonic missile. The threat is scarier than it is effective but is causing anxiety among Ukrainian civilians throughout the Ukraine. The primary reason for this anxiety is the inability of the military [Ukrainian] to shoot down the Russian MiG-31 carrying the missile."

[....]

"After about twenty years of these losses and missed opportunities, the Russian air force managed to control the corruption, revive production of a few aircraft and refurbish, upgrade and restore to flight status many existing aircraft that had been unable to fly much or not at all. Among the revived aircraft was the twin-engine, two seat 46-ton MiG-31, which was normally used for air superiority and armed with various types of air-to-air missiles."

Foxhound a modified version of the original MiG-25 Foxbat. Foxbat not a fighter plane but better thought of as an interceptor. In service first with the Soviet PVO forces. Now with Russian military aerospace.  

PVO Air Defense of the Homeland [Soviet Union] to be distinguished from the Air Force. Some MiG-25 a reconnaissance version of the plane it is true in service with the Soviet Air Force but the aircraft NOT intended for dogfighting and air superiority mission.

Still today a limited number functioning still as an interceptor AND a stand-off weapon delivery system for Russian hypersonic missile Khinzal.

Foxhound firing a long-range air-to-air missile can engage Ukrainian warplanes from a distance without ever having to cross national boundaries! But not traditional manned warplane aerial combat as understood, Red Baron style.

coolbert.