Pentagon raised threat of Israeli spying on U.S. to highest level, sources say 2 months ago
One reason is that blaming Israel for the Iran FUBAR situation is very convenient, especially for keeping MAGA on board.
The right wing pundits are already working overtime on X and elsewhere to blame Israel and concoct all sorts of explanations why Trump authorized the strike (the most amusing is that he "was possessed by demons").
Blaming Israel may have been coordinated with Netanyahu, who has nothing to lose and is probably perfectly fine with the blame as long as he gets his war and parts of Lebanon.
Blaming Israel has many historic precedents from Clinton to Trump, often through planted leaks or deliberate hot mics.