[El Gato]

The Israelis have a perfect pretext with the abduction of the Israeli soldier and killing of two others on Israeli soil,

I would not call that a pretext.

pretext A noun
1 guise, pretense, pretence, pretext an artful or simulated semblance; "under the guise of friendship he betrayed them"

2 pretext, stalking-horse something serving to conceal plans; a fictitious reason that is concocted in order to conceal the real reason

I'd call it a casus belli

Casus belli is a modern Latin-based expression meaning "occasion of war", used officially to refer to the grievances section of a formal Declaration of war. With this usage, and due to its common mispelling and pronunciation as "causus belli," — ie. resembling the English "cause" and the original Latin "causa" ("cause") — the term has the popular connotation of "cause for war".

[AdvisorB]

"I'd call it a casus belli"

I'd say you are right on target.