A simple immediate solution to high level war defence problems.

[TTPranto]

Just buff the egyptian, maori, russian coalitions at level 8.

Probably add a new defensive coalition from digital age that reduces the duration of sabotage by 5 - 7 seconds max. Decreases the recon damage percentage.

 

[oddin]

yep, an "Invading Barracks troops damage" modifier would be great in fact

 

[Rafar]

Maybe...
A considerable increase in the Sniper Tower's damage and attack speed and re-adjusting the Rifleman output from the houses by the garrison level would be enough to equalize the defenses against Helicopter and Mortar attacks.