The assault on the Iraqi city of Mosul that began this week underlines the fact that the next three months will be a perilous period in international politics. Fighting is intensifying in the Middle East. Tensions are rising between Russia and the west. And relations between China and its Asian neighbours are getting edgier. All this is happening while the US is diverted by the Trump-Clinton melodrama and the transition to a new president.

For Russia and China — two countries that are openly unhappy with the US-dominated world order — a distracted America will look like an opportunity. Both Moscow and Beijing regard Hillary Clinton with suspicion and believe that her probable arrival in the Oval Office would herald a more hawkish US foreign policy. They may be tempted to act swiftly, before she has a chance to settle into the White House.

A temporarily preoccupied America might not matter much in normal times. But big and dangerous decisions are looming. In the Middle East, the bombardment of Aleppo by Russian and Syrian government forces has led to a near-breakdown in relations between Moscow and the west. Without a common diplomatic project to hold them together, the two sides may slide into outright confrontation in Syria. Further sanctions on Russia are in the offing and the west’s military options are also being reviewed.