On Sunday, the U.S. and Iran threatened to attack critical infrastructure. Iran has stated that if the U.S. acts on President Donald Trump’s threat to attack Iranian power stations, the Strait of Hormuz—which is vital for oil and other exports—will be “completely closed” immediately. Later on Saturday, Trump set a 48-hour deadline for the strait to be opened.

Iran has effectively closed the Strait of Hormuz, which links the Persian Gulf to the rest of the world, whilst claiming that vessels from non-hostile nations may pass through safely. Around one-fifth of the world’s oil supply passes through this strait, but attacks on ships have brought virtually all tanker traffic to a standstill.

Trump stated that if Iran does not open the Strait, the U.S. will destroy its “various POWER PLANTS, STARTING WITH THE BIGGEST ONE FIRST!”

Mohammad Bagher Qalibaf, Speaker of the Iranian Parliament, responded by stating that if Iran’s power stations and infrastructure were to be targeted, critical infrastructure across the entire region—including energy and desalination facilities vital to the drinking water supply of Gulf states—would be regarded as legitimate targets and would be “irreversibly destroyed”.