they don't, and it's not really our fight, but that tunnel is the Achille's Heel for SO and the Russians.
Two lanes wide. Put a 2000 pounder through the mouth and boom ... no more tunnel and resupply to SO and the Russian forces in place get's uglier than sin.
“and it’s not really our fight”
You may be technically right. Georgia has, however, been accepted for membership in NATO, just not made an official member yet.
Over the years they have worked hard making necessary political and economic reforms to meet the membership requirements and they are almost there. It would be sad to have NATO turn its back on them now and allow them to fall to the Russians on the eve of induction into the alliance. It will mean that any promise of security NATO offers is completely hallow because it seems that an attack on one is an attack on all only if it is politically convenient.