Bush and Cheney have been chomping at the bit to go after Iran for a long time. Back in 2003, shortly after the proclamation that major combat operations had ended in Iraq, there was the widespread belief that most U.S forces would be out of the country within 6 months and available to continue the grand ol' march of freedom. One administration official pontificated that with the speedy fall of Hussein's regime in Iraq it was time to topple other undesirables in the region. The question at the time wasn't about post-invasion security or rebuilding Iraq (sorely missed oversights at the time that now leave us with U.S troops in their 5th year of occupation) but where to go next. "Real men go to Tehran" was his statement.
Almost 5 years later, the over-arching plan of "cleaning house" by going after other governments believed to be out of line with U.S policy appear to have been put on hiatus, but certainly not scrubbed. In fact, there have been several attempts to attain these goals of regime change minus the direct involvement of the U.S military, considering their unforeseen extended stay in Iraq. These attempts by other means failed, and now it is looking like a direct military operation may be back on track. Instead of acknowledging that U.S policy goals in the region may not be achievable, it appears the present administration is looking for it's chance for another try.
Before we get to today, let's look at some of the previous attempts that were made-
In the summer of 2006, Israel commenced a massive air campaign followed by a ground invasion of Lebanon, sparked by a cross border raid by Hezbollah in which several IDF soldiers were killed and captured. Israel's official stance was that enough was enough, no more mister nice guy. Their rationale was that they were going in to clean out Hezbollah, and get back their captured personnel. In actuality, the cross border raid which was the excuse for starting the war was very commonplace- these kind of tit-for tat raids have been ongoing as part of the background conflict for years. The particular raid by Hezbollah that started it was just big and bad enough for them to sink their teeth into as an excuse to do what they'd been planning for some time.
The IDF's summer campaign against Lebanon was supposed to achieve two main objectives, both of which failed:
1) Remove the threat Hezbollah posed against Israel, or at the very least render them combat innefective
2) Perform a dry-run "dress rehearsal" for what would be carried out in similar fashion by U.S and Israeli forces working in tandem against Iran later on. Basically testing out weapons and tactics as a test model on a small target for re-production on a much larger scale against a much larger target in the future.
Both of these objectives failed and so the attack against Iran was put on hold, but by no means cancelled. To start, Hezbollah being removed from the playing field was a necessity for if Iran was attacked there would most likely be a two front war as Hezbollah would attack Israel in turn. A two front war, especially where one of your enemies is sitting right next door is never desirable (technically one could argue the possibility of a three front war if you include the palestinian territories, as would probably happen with Hamas now largely entrenched in power in Gaza... but more on that later)
The dry-run objective is obvious. U.S and Israeli intel knew that Hezbollah had a large number of facilities and materiel in underground fortifications. So does Iran. The belief was that with overwhelming air power using updated weaponry, they could effectively neutralize much of Hezbollahs fighting ability, and lead to their downfall either directly or indirectly. This is how it was SUPPOSED to play out-
Israeli airstrikes cripple or destroy the bulk of Hezbollah underground facilities, take out their command, control and communications capability (or severely impair it) and leave them in such a weakened disorganized state that IDF ground forces can sweep in and mop up in a timely manner (also including insertion of special forces teams in pinprick attacks against high value targets,etc) Ideally, IDF forces wouldn't have to do much ground fighting as the popular idea was that by severely weakening Hezbollah, and dropping lots of bombs on Lebanon, that the Lebanese people would get sick of living in a bombed out country and rise up in large numbers to overthrow this weakened Hezbollah, thus ending the Israeli airstrikes.
This method is one of the most popular and has been used several times recently-
The NATO air campaign against Serbia, which did more dammage to Serbian infrastructure than their military- largely making life for the average Serbian civilian unlivable, forcing the Serbian gov to surrender to NATO demands.
Air campaigns conducted by U.S in GW1 and GW2. Nearly a month of round the clock bombings by combined forces in GW1 rendered significant portions of Iraqi armed forces innefective, demoralized or scattered, thus leaving them open for a three day ground invasion that was essentially an overwhelming hammer that crushed opposition. Again the popular uprising by civillians card was played, as Bush senior encouraged the Iraqi people to rise up against Saddam after Iraq had capitulated and withdrawn back across the border. This uprising did occur but failed.
GW2, of course we had the "shock and awe" campaign that was basically meant to send the message implied in the title of the campaign.
The same thing was supposed to happen in Lebanon, but it failed. Despite Israels best attempts at overwhelming air strikes, they were unable to severely cripple Hezbollah. Al-menar tv continued to broadcast via the web, despite their best efforts to find and destroy it. Core leadership remained alive and out of reach of IDF airstrikes and special forces raids, and rockets continued to pour over the border. When massive airstrikes failed, the IDF SHOULD have realized their mistake in sizing up the situation, but instead made a hasty, poorly planned decision to send in ground forces (tens of thousands of troops with full strength armoured units) and "smoke out" all the Hezbollah forces into the open, so that they could then be pulverized by air and artillery strikes. Hezbollah however had no illusions about the situation and chose to remain in hiding, popping out of cover when the local situation was to their advantage, conducting rapid strikes against IDF troops when possible and then melting back into cover. This frustrated the IDF to no end, and actually vastly increased the popularity of Hezbollah in Lebanon, while the U.S approved Lebanese president Saniora faced a popular uprising to unseat him with every passing day that he sat on his hands while IDF bombed and invaded his country- he was seen as doing nothing for his own people while Hezbollah was seen as mounting a hopeless struggle against the invaders. The IDF also learned that modern weaponry works both ways when possessed by your enemy- they lost several tanks quite unexpectedly to modern shoulder fired guided anti-tank weapons that have been in the arsenal of western powers for years.
Long story short, this dress rehearsal for what was going to be duplicated against Iran failed miserably. Instead of recognizing that this course of action may not work on a country like Iran or Lebanon (whose population, armed forces, geography, history and resources differ greatly from Iraq or Serbia) the plan is still on but it has just been delayed. The belief was not that the original plan was flawed, only that they didn't go big enough, and that the timing wasn't right. This time, it's quite possibly nuclear or other unconventional weapons might be considered to up the ante (development of bunker busting tactical nukes have been talked about a lot in the last couple years)
Admiral William Fallon is the commander of U.S forces in the middleast (he's General Petraeus' boss) and he knows just how out to lunch an attack on Iran would be, considering current U.S and allied deployment in theatre. He's publicly stated that he would resign before taking part in a military action against Iran. Well, yesterday he resigned. One more stumbling block to Bush and Cheney's plan for regional dominance is out of the way, just like General Eric Shinseki (chief of the Army) was a stumbling block to Iraq 2 when he gave a very realistic (and ultimately, correct) estimate of post-war problems the U.S would face. Rumsfeld didn't like what he heard, so he basically fired him. Fallon has pretty much made it clear that he's leaving because he doesn't agree with the Whitehouse's policy goals for the middleast.
With the situation in Iraq ~appearing~ to calm down somewhat with ever increasing numbers of Iraqi forces present (theoretically freeing up more U.S forces) combined with Fallon's retirement, a military action against Iran is looking ever more possible to the good folks who gave us Iraq and Afghanistan. Also, with only months left in the Bush administration this may be his last kick at the can to try and achieve his foreign policy goals in the region.
With the economy at home not doing too hot (banks just got lent 200 billion to stay afloat... a temporary measure that doesn't address some systemic economic problems) Getting into another war may be a last ditch attempt at staving off a depression at home- the dollar is currently tanking precipitously in comparison to the euro and inflation's not easing up. Other countries are starting to talk openly of dropping the dollar as the currency by which oil is bought and sold. If this happens the greenback will plummet overnight. Another war could be seen as an attempt at levelling the playing field, internationally, securing more non-renewable resources (or at least depriving other growing super powers from accessing them). After all, in his own words Bush is "the war president".