VOLGOGRAD, Russia (Reuters) -President Vladimir Putin evoked the spirit of the Soviet army that defeated Nazi German forces at Stalingrad 80 years ago to declare on Thursday that Russia would defeat a Ukraine supposedly in the grip of a new incarnation of Nazism. In a fiery speech in Volgograd, known as Stalingrad until 1961, Putin lambasted Germany for helping to arm Ukraine and said, not for the first time, that he was ready to draw on Russia's entire arsenal, which includes nuclear weapons.