Xinhuan, do you see any errors in setting it up so that when one country goes to attack another, it checks the number of previous attacks between two countries, and only if the numbers are >= 1 hit suffered for the current attacker and 0 for the defender does the DR-free retal flag get turned on?

Not that complex and it seems to work to me. Then any hits after one initial retal, normal DR rules apply.

A hits B, status of previous attacks suffered: A-0, B-0, normal DR rules apply.

B hits back, status of previous attacks suffered: A-0, B-1, this is our DR-free retal scenario.

Any further actions, status is A-1, B-1, so nothing from here on will have special retal rules apply.