For 'Warriors' training to shoot and bomb humans as part of the job description, seems the Air Force allow risk of damage by furry animals when operating our own expensive taxpayer-funded hardware at an important Base, that probably wouldn't be acceptable if an Ally were to temporarily base equipment there.
A good vermin proof fence all the way round, and a dozen Landcruisers in a line with handlers and pig-dogs to flush the hoppers out through a few opened up panels would reduce the risk factor.
A good marsupial fence, patrolled by the Airport Guards (they do have them I presume) who don't leave the gates open on weekends, - would cost less than repairs to, or loss of, a FA-18 from hopper damage, if they can't seem to use other firepower. Happens that way outside the Military, how come they are so blinkered..? We need to get something back from the Government regarding security for having ASICS, at joint user airports.
Too direct a solution, though, for some..
Needs more buckpassing, consultants reports, millions spent, etc..