From The Atlantic:
Trita Parsi, president of the National Iranian American Council in Washington, said the tit-for-tat incidents "add up to a very worrisome picture," in part because "the Iranians are absorbing all of these assassinations without seeing the pace of their nuclear program slow down to the extent it would be acceptable to the West." But if Iranian retaliations grow serious enough, he said, they could provide "the pretext for a much larger war" in which the Israelis, and possibly the Americans, launch a full attack on Iran.
Mark Hibbs, a nuclear expert at the Carnegie Endowment in Germany, says the intensity of the covert war indicates that this is where the U.S. and Israel are putting their energy for now. "If the U.S. or Israel were determined to take Iran's nuclear installations out they wouldn't be wasting time pinpointing individual scientists like this," he says. Still, he points out, that Israel's 1981 attack on Iraq's Osirak reactor was also preceded by assassination attempts on Iraqi scientists.