You want to know what happens to Israelis who are “suspected” of talking to Palestinians, or foreigners who arrive or leave Israel and are suspected of having done that?
Heck before the situation in Syria had escalated out to an all out war it wasn’t unheard of for Israeli Druze to wed Syrian nationals.
https://www.google.co.uk/amp/s/www.haaretz.com/amp/1.5104073
There is much more nuance to the situation in the Middle East than you think.