Considering the source is TASS or some other Russian news agency, such things always have to be taken with a grain of salt.
They say that football teams are told never to give the other side a reason for getting keyed up. Believe the same applies to war.
Either one of two possibilities - assuming the story is true (one does have to consider the source): first, this is rhetoric and meant to "intimidate" the American army (not exactly a tactic that has been shown to work through the ages, but it's been tried again and again), or second, these nutcases in Baghdad are serious, which would mean they think can actually win the war. The latter case means they're delusional, thus further underscoring our need to take them out.
They must think they can win the war--otherwise they wouldn't be defying us. They're just plain irrational.