Provocative hints from Israel reinforced the perception that the killing was part of an organized and clandestine campaign to set back Iran’s nuclear ambitions, which the US and its allies suspect are aimed at producing weapons. Iran says the program is for peaceful purposes only.

A column Thursday in the Kayhan newspaper by chief editor Hossein Shariatmadari asked why Iran does not retaliate, suggesting assassinations of Israeli officials and military are possible. He noted that Israel has many times said it plans to damage Iran’s nuclear program.