Benjamin Netanyahu might as well have worn a Mitt Romney campaign pin during his visit to Washington. Israel’s prime minister does not hide his disdain for Barack Obama – nor his backing for the Republicans in the November election. Mr Romney, still limping towards his party’s nomination, has pledged that if he wins the White House his first overseas trip will be to Jerusalem.

Mr Netanyahu’s unabashed intrusion into the presidential contest is worth bearing in mind when he talks up a strike on Iran’s nuclear facilities. It is pretty much common ground that Tehran’s acquisition of the bomb would represent a serious threat to Israel and to regional and global security. That does not make it sensible for Israel’s prime minister to play politics with the issue.

Raising the stakes on Iran is calculated to put Mr Obama under pressure and provide a convenient diversion from peacemaking with the Palestinians. By filling the airwaves with chilling talk about Iran, Mr Netanyahu makes it harder for others to turn the conversation to his government’s confiscation of Palestinian land in Jerusalem or the relentless expansion of illegal settlements on the West Bank.