The other issue at hand is the possibility that Iran might be starting or has already started a nuclear weapons program using Russian technology as well as other bits and pieces from countries such as North Korea and Pakistan or maybe even India (there is some debate as to whom). The IAEA (International Atomic Energy Agency) was stunned to find a large number of centrifuges (as covered in a previous article I wrote) and will file a report in June regarding their findings and recommendations. Iran has insisted that it's nuclear program is for peaceful uses only but it makes one wonder why a country with some of the largest oil and gas reserves in the world would need to use nuclear energy to help power its cities. We should keep that in mind. The Russians are the ones who have helped them build the reactor and even they have begun to quiz Iran about the reactor's use. They want assurance that Iran is not going to use the reactor to build nuclear weapons and have also stated that they will take back any spent nuclear fuel for reprocessing. This would prevent Iran from using it to build nuclear weapons.
It is hard to say for sure if Iran is developing a program to create nuclear weapons. Many signs point to the fact that Iran is indeed building such a program but we will have to wait until mid-June to discover what the UN's nuclear watchdog says about the nuclear equipment they discovered in Iran. They might find that Iran is in violation of the Nuclear Non-Proliferation Treaty, which means that their program would be under the strict scrutiny of the IAEA much like North Korea's program was for time before they put themselves off of the program. The next few weeks will be the tell all for Iran and its accusers.
The United States has every right to be nervous about Iran. They have just "torn down" two countries that border Iran (Afghanistan and Iraq) and are attempting to rebuild them in turn creating stable democratic governments. Iran, on the other hand, may be trying to undermine U.S. efforts in Iraq by sending conspirators into the country to assist in inciting riots and demonstrations against the occupation and any government that the United States might be attempting create. That, along with the other accusations cited above, constitutes the case that the U.S. is putting up against Iran.