Before we get all caught up in nationalistic furor at the prospect of another US military adventure in the Middle East I'd like to make a few points.
1) Opposing war does not mean supporting one side or the other. It is simply a recognition that war is NEVER the best option.
2) You can't claim to be acting in self-defense when you have your armies 10,000 miles away and are literally surrounding another country that you have been attacking for 70 years.
3) ALL countries, even Iran, have a right to legitimate self-defense. The right to self-defense does not allow pre-emptive acton. Pre-emptive action is OFFENSE. Period. That includes both Iranian and American actions in the middle east. If your military is outside of your country you are on offense.
4) There has been plenty of jackassery on both sides over the past 70 years but the US started this in 1953 and both sides have been at it ever since. Hundreds of thousands of lives have been lost, the vast majority have been Iranian.
While America tends to believe they are reacting to events in the past weeks and/or months, most of the rest of the world has a much longer time frame. So let's review.
In 1953 America started this conflict when the CIA overthrew the DEMOCRATICALLY ELECTED leader of Iran in order to protect British oil interests
They replaced him with a puppet government run by the brutally oppressive dictator the Shah who was friendly to American business interests. His secret police tortured and executed 10's of thousands of political prisoners over 25 years (google SAVAK)
By 1979 the Iranian people had enough and they booted out the Shah and installed an Islamic theocracy run by the Ayatollah Khomeini. In order to prevent further American interference in their domestic affairs, they took 52 American hostages. Note they did not kill them, they took them hostage and released them 444 days later on the day that Ronald Reagan was inaugurated.
America retaliated by encouraging our then ally Saddam Hussein to start a war with Iran. We supplied Iraq with chemical weapons and satellite imagery (new technology at the time and a huge advantage) showing the location of Iranian troops. At the same time the Reagan administration was secretly and in violation of US law, selling arms to Iran in order to fund another secret proxy war in Nicaragua. Over a million iranian and Iraqi lives were lost in this war which nobody won, partly because America was helping both sides.
In 1991 the US invaded Iraq under false pretenses and encouraged the Iraqi Shia (religious sect that were minority in Iraq but majority in Iran and closely connected) to rebel against Saddam Hussein. They did and the US did not defend them and hundreds of thousands were killed by Saddam helicopters.
In 2001 and 2003 the US invaded Afghanistan and Iraq (again under false pretenses) and US forces now literally surrounded the country. The US was shocked that the Iraqi Shia, who we had stabbed in the back only 10 years before, did not greet them with flowers, Many in the second Bush administration were advocating an invasion of Iran as well and they accelerated their nuclear program in true self-defense.
The US and Iran have been involved in proxy wars in the middle-east for many decades but We are the ones who overthrew their government, we are the ones who installed a brutal puppet dictator and got rich off THEIR oil, Our actions in the mid-east have resulted in hundreds of thousands of Iranian deaths. We are the one's who currently have their country entirely surrounded (see graphic). We are without doubt the aggressors in this conflict and any claim to further US aggression in the name of self-defense is complete and utter bull-****. Don't believe it.
Iran is not entirely innocent. Their government has done wrong. American lives have been lost, but they are a drop in the bucket compared to the Iranian lives lost due to America's actions and our aggression strengthen's their islamic regime by giving them legitimate reason to rally their citizens in the name of Iranian self-defense.
The only way to break the cycle of violence is to break the cycle of violence. Iran is not Iraq. It is a country of 82 million people, most of which do not support the islamic regime. It has a million trained troops and the ability to call up 11 million more reserves in case of a war. It is the 18th largest economy in the world despite devastating US economic sanctions. If you think Iraq and Afghanistan were hard battles, Iran will be orders of magnitude more difficult.
But the difficulty of winning a war with Iran is irrelevant. America has been brutalizing the country for 70 years and has no legitimate claim for military action against them. Most Iranians are moderates. It was a secular country under the Shah. The Iranian revolution occurred not because the people wanted an islamist regime but because the American supported Shah was a brutal dictator and they wanted freedom from foreign intervention. The Iranian's I have known have been wonderful people, just like you and I and they are proud of their country and love their country even if they don't love their government. Just like you and I. They are the ones who will suffer.
America simply needs to get off the oil-teat and get out of the Middle East. We are destroying the world with our oil addiction, and the world knows it. We are becoming the bad guys. If we continue in our current course we will go the way of the Greeks, Persians, Romans, Spanish, British, Germans, Russians, and every other civilization that has attempted to maintain a world-wide empire through military power. And we will deserve it.