A car bombing removed chemistry professor Roshan from his post at the Natanz uranium enrichment plant as reported in the Guardian. Riders on a motorcycle attached a magnetic bomb which exploded killing both Roshan and his driver on the second anniversary of a previous Iranian nuclear scientist's assassination, Masoud Ali Mohammadi. Over the last few years, another scientist has been killed and two others have been attacked, but survived. Iran has accused Israel of organizing this series of assaults.
America opposes terrorism, but its ally Israel is deeply implicated in this bombing as is shown in the link.
Iran claims that it nuclear enrichment facilities are are just for peaceful energy supplies and are in compliance with the Nuclear Non-Proliferation Treaty (NPT). The US, Israel and IAEA http://en.wikipedia.org/... disagree. Israel never signed the NPT and has at least 100 warheads.
Iran has strategic reasons to want a nuclear option, at least in reserve.
George Bush declared Iraq, Iran and North Korea the axis of evil. Iraq was invaded. Discussions about invading Iran are quite common. N.Korea went nuclear and no one is talking about invasion anymore.
Qaddafi gave up his attempt at a bomb and was overthrown.
Iran is surrounded by nuclear armed countries, Israel and Pakistan.
The US media always talks about the "mad mullahs" of Iran who will flatten Tel Aviv the day they get the bomb. This ignores the peacefulness of recent Persian history since World War I. The terrible Iran -Iraq War was the result of an invasion by Saddam Hussein, supported by the US.