When Senator James Inhofe took the floor of the Senate on Wednesday to argue for arming the Ukrainian military, he brought with him what he called indisputable proof of Moscow’s support for the separatists in eastern Ukraine — a poster with three large photographs of “Russian tanks entering Ukrainian territory.” In his prepared remarks, Mr. Inhofe, a Republican from Oklahoma, said the images of “Russian troops in T-72 tanks, B.T.R. armored personnel carriers, and B.M.P. infantry fighting vehicles entering eastern Ukraine” constituted evidence of “an invasion of the Ukraine by Russia.”