The Iranian government continues to stonewall European efforts to stop Iran's nuclear weapons program. Iran says it will promise to not make nuclear weapons, but won't allow foreign inspectors to confirm that. The Islamic conservatives are behind the secret nuclear weapons program, a program that enjoys wide support among a population that is otherwise hostile to the Islamic conservatives.
The Islamic conservatives who control the government are worried about American intervention, but not an American invasion. Anyone with a bit of knowledge about military strategy and history knows that invading Iran is a very different matter than invading Iraq. Iran is a much tougher opponent, even with most Iranians unhappy with their current government. Iran has three times as many people as Iraq, and the dominant ethnic group, ethnic Iranians, comprise about half the population. In contrast, Iraq has been successfully invaded several times in the last century. Not so Iran. But Iran is vulnerable to a foreign power providing support for rebels inside Iran. Unfortunately, most Iranians want change, but they don't want to use violence to do something about it. If anyone invaded Iran, most of the population would get behind defeating the invaders. Over the last five thousand years, there have been few successful invasions of Iran. The country has geography, and a tough, resourceful population, to provide a formidable level of resistance. But the United States could do a lot more to support the numerous anti-government sentiment inside Iran. That support may be happening already. By providing money, equipment (radios, computers, cell phones) and information about what Islamic conservatives are doing to the population, but trying to keep quiet, the United States just increases the popular pressure against the Islamic conservatives. Unfortunately, American pressure on Iran to stop its nuclear weapons program is generally unpopular within Iran. Most Iranians see the possession of nuclear weapons as neccessary for national defense, and something a nation of Iran's history and stature deserves.