Iranian paper calls for retaliation against Israel

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 U.S. and its allies suspect are aimed at producing weapons. Iran says the program is for peaceful purposes only.

Iran's nuclear confrontation with the West had already been escalating in the weeks before the killing, with the U.S. tightening sanctions against Tehran, and Iranian officials warning that they would shut a waterway vital to global oil shipping in response.

The Wednesday assassination of Mostafa Ahmadi Roshan - at least the fourth targeted hit against a member of Iran's nuclear brain trust in two years - has heightened tensions even further.

Iran's Supreme Leader Ayatollah Ali Khamenei blamed both Israel and the U.S. In a message read on Iranian state TV, he said the killing was carried out "with design or coordination of the CIA and the Mossad," Israel's spy agency. He pledged that Iran would punish those responsible.