A Marine uses a handheld electronic device at Marine Corps Base Quantico in March 2013. US Marine Corps/Sgt. Isaac Lamberth Russia's war in Ukraine has vividly demonstrated the consequences of communications failures. For US military leaders, the war underscores the need to manage their forces' electronic signatures. To do that, younger troops will have to unlearn some habits, the Marine Corps' top general says. The use of new technology on the battlefield has prompted the US military to rethink its operations as it prepares for a future conflict with a technologically advanced adversary, and many of its changes have been…