The following in an edited version of a paper I presented two weeks ago in a debate on the topic "When should the US use force abroad and what lessons should we learn from America's use of force in Iraq and how should those lessons inform decisions on future military missions abroad?"

There are really two questions here – when is the use of force justified in the context of the key word "abroad" and what have Americans learned regarding overseas interventions from the Iraq experience. As a foreign policy adviser for Ron Paul in 2008 and 2012, I lean in a non-interventionist direction, but that is at least somewhat due to that fact that recent interventions have not worked very well and have in fact increased the number of enemies rather than reduce them while also killing nearly 7,500 American soldiers and more than a million inhabitants of the countries Washington has become entangled with. One might also reasonably argue based on post 9/11 developments that destabilizing or attacking other countries consistently makes bad situations worse and has a tendency to allow problems to metastasize. This is sometimes referred to as blowback.

Nevertheless, anti-intervention does not necessarily mean anti-war when war becomes the only option to protect vital interests, but armed conflict cannot be entered into lightly. There is in fact a simple answer to when to use force: it is to defend the United States itself against a clearly defined threat to the country or to a genuine vital interest. Indeed, unless a vital interest is threatened the US has no right to intervene anywhere. And how to use force is also simple: it is up to Congress to declare war as required by the Constitution. But the Constitution of the United States did not envision major deployments of American soldiers, sailors, Marines and airmen overseas, nor did it consider the existence of more than 1,000 military bases worldwide. Indeed, the US has not faced a domestic armed threat since Pancho Villa raided New Mexico in 1916, so it is necessary to consider war-making in a contemporary context.

Those who see America's future wars as taking place "abroad" are to be sure recognizing the geographical isolation of the United States but they are also essentially promoting the principle that the country should best be defended preemptively and at a distance. Any argument for forward-defense should be based on "Just War" doctrine and must include an imminent threat. It would not include the currently fashionable humanitarian interventions, democracy promotion by force of arms, or wars of choice.

To cite the example of Iraq, if Saddam Hussein had indeed had gliders capable of flying across the Atlantic Ocean with chemical or biological weapons and had the intent to use them then attacking him would have been fully justified with or without UN permission. But lacking capability and intent to actually threaten the United States, avoiding overseas military engagement is invariably the most ethical and realistic option. Unleashing violence on a foreign government and its captive civilian population inevitably produces unforeseen consequences that result in haphazard mission creep long after the initial targets of the attack have been destroyed.

Even when a military initiative is considered inevitable it should conform to the so-called Colin Powell doctrine: it should be an unambiguously vital interest, it should be the last available option, it should have a clear and achievable objective with risks and costs clearly explained, consequences of the action must be understood and it should have a timetable and exit strategy. The American people must understand and support the mission and ideally foreign support should also be in place. It has been alleged that Powell also subsequently added the Pottery Barn rule – "once you break something, you own it." This has been interpreted to mean that regime change has consequences. The successful invader becomes the new government and has to figure out what to do with the millions of people that now have to be fed, housed and taken care of.

The lessons learned from Iraq are several and they reflect failure to satisfy some key elements of the Powell doctrine. Active monitoring and discussions over Iraq's weapons were ongoing when the decision to go to war was made by Washington so the war was not a last option. There was in fact no vital interest at stake, though that might not have been clear to everyone at the time. The objective to bring about regime change was both clear and easily achievable but there was not much consideration of what would happen on the day after or of consequences both for the region and the Iraqi people. There was no timetable and no exit strategy and the mission morphed into nation building, not a fit task for anyone's military and also an endeavor which was already in considerable trouble in Afghanistan.

All of the complications involving Iraq were exacerbated by a failure in intelligence from start to finish. The US intelligence community exists in theory to supply policy makers with objective information regarding what is going on in the world that might threaten either the United States or its interests. Information is its sole product because the intelligence agencies traditionally are not involved in policy for very good reasons – information untainted by political considerations, even if it is ignored, must be provided to permit the best possible decision making.

To be sure the line between intelligence and policy has been crossed more than once in the past seventy years and information has often been politicized as in the Soviet estimate, which made Moscow appear to be both more threatening and capable than it actually was. But the lead up to the Iraq war took intelligence tampering to a whole new level. Sir Richard Dearlove, head of Britain's MI-6, and a key player in the Anglo-American effort to make a case against Saddam, said subsequently that the intelligence has been "sexed-up" to make it more convincing regarding Iraq's alleged weapons of mass destruction. The so-called Downing Street memo confirmed that the "intelligence and facts were being fixed around the policy" rather than vice versa and Dearlove specifically claimed that questionable evidence was being described as solid in making assessments.