Iranian state media reports explosions in several coastal cities, including Bandar Abbas, Konarak and Chabahar.
At 11 p.m., additional explosions were reported on the Iranian island of Abu Musa in the Persian Gulf as well as in a village near the coastal town of Sirik, Al Jazeera reports.
The US military command Centcom confirms the attacks. The goal of the attacks is to weaken Iran's ability to threaten shipping in the Strait of Hormuz, it said, among other things. The US has accused Iran of being behind attacks on three merchant ships in recent days.
US President Donald Trump threatened to attack Iran during Wednesday's NATO summit in Turkey. "We are going to hit hard tonight," he said.
Spokespeople for the Iranian regime have called Trump's comments "abhorrent." Iran, in turn, has said that the country, along with its "armed branches across the region, have their finger on the trigger."
The US and Iran agreed to a ceasefire in early June as part of a larger agreement to reach a long-term peace solution.
