Ending a war is seldom straightforward. Even agreeing to a ceasefire comes with complications. Though Ukraine signed up to a 30-day ceasefire proposal after discussions with the US in Jeddah this week, the joint statement between the two does not begin to explain how a halt in fighting might be enforced. “Monitoring has to begin immediately,” says John Foreman, a former British defence attache to Moscow and Kyiv. “If there’s meant to be a 30-day ceasefire, the big question is whether it is adhered to.” Given Russia has a record of violating ceasefires and peace agreements, a robust process is...