A quarter of the foreign military students are from Saudi Arabia. Every single one should be interrogated and sent home until our vetting procedures are tightened up.
Train them in their own country.
Ditto that.
Do it now .
It is impossible to vet a Muslim.
Even the Muslim often has no idea if or when he might do his duty as per the Holy Quran and wage Jihad.
You could vet one today, and it would be completely true that he is no threat, and tomorrow he does his duty.