Something that other posts touched on obliquely but didn't fully address--

The assumption that Iran is a "threat," a set piece in a lot of news reporting and political analysis right now, follows the same pattern as the assumption that Iraq was a threat in 2002. There's a lot of talk about Iran's oppression of its own people, which is true from all evidence, but analysts often blur this into a more ambiguous direct threat to the U.S., backing up their assertions with the idea that Ahmadinejad et al. are "irrational."
Yet they seem to be pursuing a remarkably rational game of brinksmanship. If they appear irrational, it gives them an advantage. N. Korea follows a similar strategy. Iran's "irrationality" has thrown American politicians into apoplectic fits, which from Iran's perspective must be very amusing. What I'm saying is, the direct threat from Iran has been hugely inflated--leaving aside indirect involvement in Iraq, which could be handled by negotiation.

Therefore, Hillary's militant, frantic stance does not indicate a level-headed approach, regardless of what words she uses. However, it does prove to be a calculated political move, reacting to American media trends rather than diplomatic reality.