Frigate goes down off Sri Lanka as Washington and Israel step up their offensive and promise to hit ‘deeper’ targets in Iran

• Middle East crisis – live updates

A torpedo fired by a US submarine sank an Iranian warship off the south coast of Sri Lanka as the Trump administration followed through on its threats to destroy Tehran’s military and political leadership.

At least 87 Iranian sailors were killed in the attack on the Iris Dena on Wednesday. The frigate was sailing in international waters as it returned from a naval exercise organised by India in the Bay of Bengal. The torpedo strike prompted questions from former US officials about whether Washington’s aim of eliminating all of Iran’s military breached international law.