Seumas Milne writes: They don’t give up. After a decade of blood-drenched failure in Afghanistan and Iraq, violent destabilisation of Pakistan and Yemen, the devastation of Lebanon and slaughter in Libya, you might hope the US and its friends had had their fill of invasion and intervention in the Muslim world.

It seems not. For months the evidence has been growing that a US-Israeli stealth war against Iran has already begun, backed by Britain and France. Covert support for armed opposition groups has spread into a campaign of assassinations of Iranian scientists, cyber warfare, attacks on military and missile installations, and the killing of an Iranian general, among others.

The attacks are not directly acknowledged, but accompanied by intelligence-steered nods and winks as the media are fed a stream of hostile tales – the most outlandish so far being an alleged Iranian plot to kill the Saudi ambassador to the US – and the western powers ratchet up pressure for yet more sanctions over Iran’s nuclear programme.

The British government’s decision to take the lead in imposing sanctions on all Iranian banks and pressing for an EU boycott of Iranian oil triggered the trashing of its embassy in Tehran by demonstrators last week and subsequent expulsion of Iranian diplomats from London.

It’s a taste of how the conflict can quickly escalate, as was the downing of a US spyplane over Iranian territory at the weekend. What one Israeli official has called a “new kind of war” has the potential to become a much more old-fashioned one that would threaten us all.