Britain, France and Germany have threatened to trigger a “snapback mechanism” to reintroduce UN sanctions over Tehran’s atomic programme that were lifted under a now moribund 2015 Iran nuclear deal.

A powerful storm kicked up a towering wall of dust that rolled through metro Phoenix on Monday, darkening the sky, blinding drivers, knocking out power and grounding flights at one of the nation’s busiest airports.

President Donald Trump said on Tuesday he is prepared to impose economic sanctions against Russia if Vladimir Putin fails to agree to a ceasefire, warning of serious consequences.