British intelligence chiefs have warned that Israel will launch military action to thwart Iran’s nuclear weapons development efforts as early as Christmas, according to a report in The Telegraph.

The United Nations’ International Atomic Energy Agency this week confirmed that Iran is developing a nuclear warhead that could fit on an existing missile.

“Sources say the understanding at the top of the British government is that Israel will attempt to strike against the nuclear sites ‘sooner rather than later’ — with logistical support from the U.S.,” The Telegraph reports.

British ministers have reportedly been told to expect Israeli military action, and a senior Foreign Office official said the attack is expected “as early as Christmas, or very early in the new year.”