Iran threatened Israel and the United States on Monday with revenge for last week’s assassination of a nuclear physics professor in a mysterious bombing near his home in Tehran. Iran accused Israel and the American Central Intelligence Office (CIA) for the assault, which it stated was carried out by opposition elements acting as proxies. Assassinations are rare in Tehran.

The professor was not a prominent political figure and is not recognized to be linked to the Iranian nuclear program, yet Iranian President Mahmoud Ahmadinejad explained that the murder was a “grudge” action carried out in “Zionist style.”