Martin Chulov writes: Five years of political capital, over a million tonnes of weapons, tens of billions of dollars, Russia’s role as both dominant regional presence and rising global force – these are all at stake if Vladimir Putin abandons Syria’s leader.

This is the reckoning faced by the US secretary of state, Rex Tillerson, as he travels to Moscow to try to prise the Russian president away from his support of Bashar al-Assad in the aftermath of last week’s nerve agent attack on Khan Sheikhun.

Ahead of the first high-level summit between Russia and the US since the election of Donald Trump, hopes have been raised that the atrocity could be a catalyst for change in a country destroyed by war and failed by global politics.

Those hopes, however, are almost certain to be dashed. Throughout the conflict, and especially since the Kremlin doubled down on its support for Assad in September 2015, Russia has pursued a win-at-all-costs strategy, which has regularly defied the bounds of modern warfare and edged Assad’s regime towards a winning position on the battlefield. [Continue reading…]