As Russia warned Ukraine on Tuesday that it could run out of natural gas within two days because of a dispute over payments, Britain said it was sending military trainers to aid Ukrainian forces while European diplomats labored to patch up a flagging peace agreement in eastern Ukraine . The warning by Aleksei B. Miller, the chief executive of Gazprom, the state-controlled Russian energy behemoth, illustrated how the hostilities between Russia and Ukraine are hardly limited to the battlefields in eastern Ukraine, where a cease-fire agreed to nearly two weeks ago has still not fully taken hold . Russia has long used its muscle as the region’s major energy supplier to wield political and economic influence, particularly in disputes with Ukraine and other former Soviet republics. A bitter feud over gas payments has been a subplot of the wider political dispute between Moscow and Kiev over the […]