US President Donald Trump has said he has launched a "major combat operation in Iran". In a video message posted on social media, he claimed that Iran is expanding its nuclear program and planning to develop missiles that can reach the United States.

The US and Israel launched military strikes against Iran on Saturday. International media reported that the first attack took place near the office of Supreme Leader Ayatollah Ali Khamenei in the capital Tehran. Smoke was then seen rising from various parts of the city.

It was not clear whether the 86-year-old Khamenei was in office at the time of the attack. He has not been seen in public in recent days due to rising tensions with the US.

The attack came as the US is deploying fighter jets and warships to the region as it steps up pressure on Iran for a nuclear deal. An official, speaking on condition of anonymity, said the Israeli campaign targeted Iranian military, government symbols and intelligence structures.

Roads leading to Khamenei's compound in Tehran have been closed, while witnesses said other explosions were heard across the capital. Iranian state television confirmed the blast but gave no further details. Iran has closed its airspace and suspended mobile phone service. Neighboring Iraq has also closed its airspace, the transport ministry said.

Sirens have sounded across Israel and people have been warned to be on alert for possible missile strikes. Israeli hospitals have implemented emergency protocols and are preparing to move patients and surgeries to underground facilities. Israel has also said it has closed its airspace.