Who are you going to trust: a high school dropout branded as a traitor, a loser and a spy, or a four star general who heads the world's largest intelligence agency? I'll take the high school dropout.
Among all human failings, mistakes, crimes and betrayals, lying is unique: you can only do it once. After that, no one believes you. This moral rule applies to individuals as well as groups of people. Can you apply it to an entire government? I suppose it depends on the seriousness of the lie, and exactly who tells it.
Do you think the United States government is trustworthy? Do you believe what its representatives say?