I consider Russia to be more of a threat than Iran, Iraq and North Korea combined. The Russians have a very large and extensive army that are ready to fight at any time. Russia also has many weapons that could defeat just about any country very quickly and easly. This makes Russias army one of the more dealy forces .
Iran seems to making peaceful gestures towards reconciling with America. Iraq isn't much of a problem, and that leaves North Korea is a dangerous rogue nation. Russia, however, poses a complex security problem. They still have a lot of nuclear weapons, and they have the capability to launch them with intercontinental ballistic missles.
Yes, all of these three countries combined are not near as bad as the russian army would be to fight. They have a huge amount of men and a huge amount of equipment that could take any nation straight to its knees if they wanted to do it at any time.
Russia has never been a significant threat to the United States, or any other first world nation. The U.S.S.R. was a significant threat at one point, but the resolution of the Cold War more or less deflated that regime. While Russia and the west may not have the most amicable of relations, they are certainly better than those of other nations. North Korea alone is more volatile -- and, therefore, dangerous -- than Russia.
To be honest, this comparison is probably pretty close. Considering Iraq no longer has Saddam ruling it. That Iran is under a new administration and seem to be a bit more reasonable. North Korea, by far is the craziest country of them all, but also very poor. I just think the Russian people will keep their leader in check. That is why the 3 countries together are worse than Russia.