It is the rout phase. Can the Greek unit in Y5 low crawl to Y4.
One argument is that the Greeks cannot see AA6 so they could rout away from the Adjacent unit to Z5, albeit they then would be unable to rout further without risking interdiction so would surrender. Due to the unit in Y6, Z5 can be ignored so they can rout toward X3 and use low crawl to avoid interdiction.
The other argument is that ultimately the Z5 path would end up risking interdiction so therefore they surrender as they are unable to rout without risking interdiction or using low crawl.