The US says it is striking Iran after President Donald Trump earlier threatened to “hit them hard”.
Iranian media has reporting explosions in areas along the country’s southern coast and in Iranian-controlled islands in the Gulf.
US Central Command (Centcom) says the strikes are in response to “recent unjustified aggression against commercial shipping and civilian crews” in the Strait of Hormuz.
It follows US strikes on Tuesday, which Centcom said were in response to attacks on three commercial vessels transiting the strait.
Iran said it has responded with retaliatory attacks on US military sites in Bahrain and Kuwait in the early hours of Wednesday.
Responding to Trump’s comments earlier, Iran’s foreign minister also said: “We do not answer vulgarity with vulgarity, but with action: fearlessly and with great valour”.
