DUBAI - Iranian authorities have arrested hundreds of people and executed half a dozen in a sweeping security crackdown that analysts say is aimed at exerting control after a brief but punishing war with Israel exposed Iran’s deep infiltration by Israeli intelligence.

The fast-changing war between Israel and Iran, in which the U.S. recently inserted itself by targeting Iran’s nuclear sites, has caused a mix of emotions — including fear and uncertainty — among many in the Iranian diaspora in America and also showcased differences of opinion over the country’s future.