Roosevelt masked his veto of the bridge as a purely military decision

Evidence

But Roosevelt had learned from the 1935 controversy. Then, during a press conference, he had incautiously allowed himself to be identified with “Ickes’ ” decision. Now, when, at another press conference, reporters questioned him about the “Woodring” decision, the President said firmly that the decision had been that of Woodring and the War Department alone. Pressed to say whether or not he agreed with the decision, he said he had no opinion on it at all. Try as Moses would to link him with it, he could not do so. The fox had left no tracks. — Robert A. Caro, The Power Broker, 2866