WE B F
Reinforce with Tonka 4s and, probably, 3s. Repulsing an air supported amphibious assault with 3s (4 EA max and more likely 3 EA) isn't going to work. FI is one of the few places on the planet where we don't need a carrier; unless we're daft enough to lose it again.
The fact we can reinforce the air component faster than they could marshall and launch an assault is the deterrent.