Neocons, however, are the single greatest threat to world peace since McCarthyism.
Surprisingly, I somewhat disagree with you here - and even on McCarthyism. The reason is because they're symtpoms of larger issues.
On Neocons, ask this - how much of a threat are revolutionary communists who want to militarily overthrow the US government? Not much, because while their ideology might be dangerous if it had power supporting it, it doesn't, and they pose little more risk than annoying you with a rally. Similarly, Neocons themselves could be just Dick Cheney sittting with them on a park bench muttering about the commies in power and no one cares what they have to say - it's the fact that there are major powers who are ready and willing to support them that's the real problem, as in, if it weren't the Neocons, it'd be some other group providing a similar agenda, and the real problem is how much power there is aligned for that type of agenda. The military-industrial complex, the radical right think tanks, the right-wing media supporting them, and so on.
Every modern president is under pressure to follow something like a Neocon agenda. Some follow more willlingly than others.
Rarely, as with Eisenhower in his farewell speech after 8 years of largely following their agenda, or JFK after the Bay of Pigs, you see presidents who directly oppose them.
As long as the global political structure rewards the pursuit of power and empire, the problem will exist.
And at times, there is a choice among the lesser of evils - the US behaving imperialistically, of another nation doing so in the vacuum if we don't.
While it's easy to see the PNAC doctrine call for the US to dominate the world and concluce that PNAC are an evil cabal who can make the US do that, that's not quite accurate, rather they are happening to push an agenda which has too much support because of everything from the military-industrial complex to an American populace who is too pro-war, too easily manipulated, too ignorant, too complacent.
Similarly, McCarthyism existed because there were big ijnterests in our nation who were shut out of power by FDR's popularity, and the Republicans who would represent them found that the line of 'protecting America from the traitors in our own government and the evil abroad' would sell to the public and return them to power, as it did in 1952 after weakening the democrats after WWII. The powerful interests who wanted political power back are why McCarthyism had powerful backing.
Note in both cases that the actual players - McCarthy, Dick Cheney, etc. - are almost incidental compared to the fact that there are powerful forces - massive sums of money to be made - creating the pressures for those people to get support and be able to get power for those agendas.
Get rid of the Neocons, and you might make a dent to their agenda, but the situation will still have powerful forces pressuring that direction.
What we need to do is to fix the underlying problem - strengthen the UN so that the problem every nation faces of having people who want to pursue power aggressively and violently have less incentive to do so, change the legal doctrine saying US corporations are legal persons giving them all kinds of inappropriate rights to fight the people's interests and agendas, fix campaigin financing that lets the monied agenda be too influential.
