the bomb or missle would not get here, between the air to air lasers, ground to air lasers, kinectic bombardment it wont make it
there are no operational air to air nor ground to air lasers, if those Russian nuclear subs launch their nukes you can kiss a whole city goodbye.
there will be no winners in a total war with Russia.
The US does have a missile defense system however it has not been tested in "real world" scenarios. It is anyone's guess if it will be able to stop a massive nuclear attack on the US by a country that has as many nukes as Russia (100% success rate at destroying thousands of nukes)