They're not at all! They put up that act to make people believe they are so that it introduces an element of uncertainty into the calculation. Like the parent said, going to war with the US is suicide, which no rational leader would do but a seemingly irrational/insane leader might. This adds an element of risk to the US and make us think twice about intervening.
Given the situation they have been in for the past 60 years, and the political climate of the past 17, their behavior has been quite rational.