Country 1 is a well developed nation which has been recently attacked by terrorists: 3000+ dead. Country 2 is a so-called rogue state. It is lead by a dictator. It is attempting to study and create WMD. It is thought by analysts within Country 1 that this country would be perfectly willing, indeed, that it would jump at the chance, to sell what it can create to eager young, energetic terrorists. Country 2's regime hates Country 1 and Country 1 publicly wants regime change in Country 2. One last thing. The UN has forbidden Country 2 from even researching WMD technologies. Both countries are members of the UN. Oh yeah, one last thing. Country 2's Dictator is a cruel, unstable, murderous man blah blah blah.
But there's a problem. Country 2 has no WMD yet. It isn't an imminent threat. Lets imagine further that Country 2 is researching how to become an imminent threat quickly. That is, to create WMD "from scratch" in a very short amount of time. Lets imagine that Country 1 somehow knows all of this. And Country 1 has almost no defense against such a threat.
So lets pause the situation and do some cost - benefit analysis. Country 2 could become an imminent threat soon. All it takes is a few breakthroughs. After that point, Country 2 becomes a major threat because any attempts to remove this country's power of WMD will have great costs. WMD will be used on the invading troops! How long will it take for Country 2 to be an imminent threat? This is impossible to determine. The UN has searched Country 2 and has not found a "smoking gun" but Country 2 refuses to let the UN interview the scientists in private. Country 2 has attempted to shoot down aircraft from Country 1 which are enforcing a no fly zone. Country 2 knows very well that if it wants WMD, it is going to have to either hide what it has (not very difficult with miles and miles of desert to drive off into and GPS to find them when you want them) or learn to develop them quickly. Probably both. Country 2 is researching this. Diplomacy has failed and it is becoming obvious that Country 2 is hiding something. It is possible that Country 2's dictator thinks he has more WMD then he actually does.
Country 1 is lead by a President, it has a Congress and House much like our own. But it has better intelligence than we apparently had. Country 1 knows that Country 2 could be an imminent threat within a year or less.
What should the President do? He has the power to send the armed forces over for 30 days whether or not Congress agrees. He can do this even if the people of Country 1 don't like it.
Seriously, figure out what you think the President of Country 1 should do before you read on.
Now consider: The news, and thus The People of Country 1 have discussed at length what should be done. Some want war. Some never want war. The President's opponents are doing exactly what you'd expect. There is no consensus. Is there ever a consensus? Some people want to ignore the murderous nature of the Dictator of Country 2. We cannot be the police of the world. Some people are saying that Country 2 is not yet an imminent threat.
What should the President do? If he attacks now, he can remove an evil man from power, put The People of Country 2 into self-governance and remove a possible threat before it becomes truly painful to remove. What should the President of Country 1 do? It is his job to protect the people of Country 1 even if The People don't see the danger.