The US ambassador in Kiev Geoffrey Pyatt has waded into the debate about Russia’s intentions with Ukraine by tweeting a photo reportedly showing the build-up of Russian troops on the border of ex-Soviet Republic. The tweet, with the English words “proof of RU military buildup”, shows three successive photos of a field in Rostov-on-Don, Russia taken in October last year, March and April. The first photo shows an empty field, while in the March photo there are arrays of armoured vehicles. In the final photo, dated April 2, the field is densely packed with what appear to be vehicles and tents. More