Political analysts often use chess as a metaphor to describe world affairs. States and peoples move around the board struggling to make incremental gains. Every now and then, a grandmaster arrives and transforms the game with a new and unexpected gambit – something like Richard Nixon and Henry Kissinger’s “opening to China” in 1972.

At the moment, international politics looks badly in need of some brilliant new thinking. Many of the big powers are in a diplomatic mess. America is back at war in the Middle East. Russia is isolated. China has antagonised almost all its neighbours. Britain is drifting to the margins of Europe. The geopolitical chessboard seems to cry out for bold new moves. What might they be?

The new Yalta defence: Opinions differ as to whether Vladimir Putin is a political grandmaster or a fool who is on the verge of being checkmated. The Russian president’s admirers saw his annexation of Crimea as a bold gambit that caught the west off-guard. (At the time, Mr Putin’s admirers in the west sometimes said: “He’s playing chess and we’re playing checkers.”) But with the Russian economy reeling, it looks increasingly like Mr Putin’s move was too impetuous. In an effort to recover ground, the Russians are now pursuing a game plan, that could be called the new Yalta defence. This harks back to the period when leaders such as Josef Stalin, Franklin Roosevelt and Winston Churchill really did treat the world as something like a global chessboard – and divided postwar Europe into spheres of influence. Mr Putin’s dream is to be granted a renewed Russian sphere of influence over most of the former Soviet Union. Some in the west are tempted by a new Yalta. Others find the idea sinister and distasteful. Mr Putin did himself no favours when, discussing the idea of great-power bargains, he suggested the Hitler-Stalin pact of 1939 had got an unfairly negative press. Bad move. Chances: 3/10