Ukraine is digging in as the Kremlin steps up its offensive

The construction of three new lines of fortifications in Sumy province is part of a billion-dollar Ukrainian scheme to shore up defences ahead of an expected Russian summer offensive. Diggers are working around the clock, as they are in Kharkiv, Zaporizhia and Donetsk provinces, where the main push is expected. Construction follows a master plan of interlocking trenches, underground command-points, observation posts, and sleeping quarters that double as field hospitals. The general rule is that army brigades build the first line. Engineering forces, local authorities and occasionally local businesses take care of the rest. The outer line, about 30km back, is the sturdiest, built in relative calm with diggers and reinforced concrete. After a long delayed start, the first part of the project is due to be completed by the end of the month. The question is whether that will be soon enough.