Crucially, the show of force in Syria and the show-and-tell of spycraft both come as Iran is constrained from plunging into a shooting war with Israel, either by itself or by proxy. Its own public is increasingly restive. Its close ally in Lebanon, Hezbollah, which might otherwise be counted on to retaliate against Israel, is reined in, at least for the moment, by elections on May 6, in which it is fielding candidates.
Most of all, with President Trump set to announce his decision on the nuclear agreement by May 12, Iran is unlikely to give Mr. Trump any fresh excuses to quit it.
“That’s just an opportunity for Israel to do what needs to be done, and at relatively low cost,” said Daniel Shapiro, the former United States ambassador to Israel under Mr. Obama.
Analysts said Mr. Netanyahu’s fight to arrest Iran’s conventional-arms buildup in Syria was linked not merely by coincidence of timing to his efforts to deny Tehran a nuclear option. Just as North Korea amassed a huge arsenal of artillery to threaten Seoul while it worked to develop nuclear arms, Mr. Shapiro said, Iran is seeking to threaten Israeli territory, with drones and precision-guided missiles from within Syria, “while it uses time and negotiations and delays to advance their nuclear ambitions.”
Amos Yadlin, a former chief of Israel’s military intelligence who now heads the Institute for National Security Studies in Tel Aviv, said Iran’s nuclear and conventional threats were “aimed at the same goal: to destroy Israel.”
Mr. Yadlin said the nuclear deal had succeeded in stopping Iran from pursuing nuclear weapons for a number of years.
“So they built a conventional force against Israel in Syria — with ballistic missiles, with precise guidance,” he said. “And this is the most dangerous threat towards Israel today in 2018.”