The “law” of war deals with wars between nations.
Wars between nations used to be the norm. Many people considered warfare to be fine and noble, the highest type of human endeavor. "Is not peace an element of civil corruption and war a purification, a liberation, an enormous hope?" (Thomas Mann)
Those ideas wore themselves out in the trenches of the First World War.
The nations of the world, including the United States, renounced war as an instrument of policy in 1928 by signing the Kellogg-Briand Pact. Germany and Japan also signed.
Law – even something so apparently distant and abstract as international law – is always, at its birth, an attempt to deal with real situations: here’s a problem, it keeps coming up, let’s set a rule on how to deal with it. The machine made slaughter of the Second World War was even worse than the machine gun slaughter of the First. The response was - in effect – “didn’t you learn anything the first time? You signed off on it. Going to war was a violation of that treaty. That’s one of the legal foundations of putting you on trial.”
There were thirteen sets of trials at Nuremberg. The first was of twenty-one of the Nazi leaders. All of them were indicted for planning and/or waging an aggressive war. Twelve were convicted of those charges. Seven of those twelve were sentenced to death by hanging.
If Kellogg-Briand was binding on Germany and Japan in the middle of the 20th Century, it must be argued that it is binding on America at the start of the 21st.
Furthermore, the United States was the leader in setting up the war crimes tribunals. We supplied several of the prosecutors and we supplied several of the judges who hung the Nazis convicted of committing the “supreme international crime,” a “war of aggression.” The United States was also the chief architect of the United Nations. The UN charter, which renounces war, has treaty status, and the US is a signatory.
The right to self-defense is complete.
Nothing limits a nation’s right to defend itself. If it is attacked.
2) Civil Wars:
All the rules dealt with wars between nations.
It did not deal with wars within nations or empires.
In order to make wars between countries illegal it was necessary to give sovereignty and territorial integrity almost sacred status. The first commandment and the commandment that overruled all others, was: do not enter another country.
It was impossible to deal with someone else’s civil war or internal genocide or a war for independence without crossing a border, so those wars were left out of the equation. They were internal matters, neither legal nor illegal in international terms.
Those kinds of wars are going on constantly. Most years we can find between twenty and thirty ethnic conflicts, tribal wars, internal political conflicts or full blown civil wars going on around the globe.
3) War by Invitation:
If a government in a civil war or under attack calls for help, a foreign power can come in by invitation. That was the legal circumstance under which the US was in Vietnam. The Russians claimed they were invited into Hungry in 1956.
4) UN Wars:
The United Nations may also authorize a war in order to keep or restore the peace. The Korean War was a UN police action. The war to drive Iraq out of Kuwait was authorized by the UN.
We constantly hear that international law is worthless and never stops anyone from doing anything. We constantly hear how ineffectual the United Nations is. It may come as a surprise, then, to discover how very, very few wars there have been of the type outlawed by the UN Charter since 1945.
Those exceptions include: Iraq’s invasion of Iran; Iraq’s invasion of Kuwait; China’s 20 day invasion of Vietnam in 1979, Vietnam’s invasion of Cambodia to suppress the Khmer Rouge in 1979; the invasion of Israeli territory by six Arab states in 1947; the invasion of Egypt by Great Britain, France and Israel in 1956; the invasion of Israel by Egypt and Syria in 1973; US troops sent to the Dominican Republic in 1965; US attacks in Cambodia during the 70’s.
That’s about it.
I have not included a host of minor clashes. Not state sponsored or assisted terrorist attacks like Lockerbie, nor the US taking shots from the air at Libya. Not the Intifada, not shots fired along the border in Kashmir.
I have not included the US invasions of Panama, Grenada, Afghanistan and Iraq, Israel’s Six Day War and the raid on Osirek because they have all been claimed to be “preemptive war.”
The number one, iron clad justification for war is self-defense.
But what if a violent enemy, which has sworn your country’s destruction, is massing on your borders? Moreover, you have “intelligence” that tells you they plan to attack. Do you have to wait for the attack before you defend yourself? Does self-defense mean that a country has to let the enemy strike first as the Japanese did at Pearl Harbor?
Or can you “preempt” them and attack first?
TO BE CONTINUED: We are currently engaged in two wars based on an extension of the idea of preemptive war. It is written down as the National Security Strategy and referred to as the Bush Doctrine. It is worth understanding what the legal tradition has been and why it has been that way. How the NSS/Bush Doctrine departs from it, and if it is legal. Or illegal. And why that matters.