Step 1: He should immediately announce the revocation of all Australian passports issued to Aussies who made aliyah to Israel. He can do that without needing any "proof" of "Israel's guilt" i.e. it is enough for him to know that allowing Oz-born olim to retain their passports leaves a gaping security hole that SOMEONE is abusing. That hole therefore must be plugged, and pronto, and the quickest way to do it is to revoke those passports. Step 2: If Australia **does** find evidence that proves Israel is responsible for forging Aussie passports then he needs to sever diplomatic relations with Israel. After all, the Aussie govt warned Israel not to do this.....
U.S. army tests ballistic missile interceptor off Hawaii (AP)
from the article: Report: Australia already warned Israel against faking passports