Minor but important point
The Bush administration isn't proposing breaking the ABM treaty.
The 1972 ABM treaty between the USA and the Soviet Union has a provision for withdrawal, after a 6 month notification. What Bush proposes, correctly in my view, is that the USA properly withdraw from this archaic relic of the now dead Cold War, in strict accordance with the provisions of the treaty itself.
Thus it is incorrect for anyone to accuse Bush of 'breaking treaties', or the USA of not 'keeping their word', at least as far as the ABM is concerned.