While we've been distracted by a flurry of intelligence releases on Syria's chemical weapons strikes - and the ongoing saga over the United States' response - many have overlooked another intelligence report pertaining to weapons of mass destruction with severe implications for America's red lines and credibility in the Middle East.The International Atomic Energy Agency, the world's nuclear watchdog, reported that "Iran plans to test about 1,000 advanced uranium enrichment centrifuges it has completed installing." As Iran's enrichment capabilities increase, its breakout time - how long Iran would need to rapidly amass enough highly-enriched uranium for a nuclear weapon - is dropping considerably. In the next year or two, Iran's breakout time could drop to about 10 days: too short of a window for the United States to reliably respond before Iran could secure enough material for a bomb.America's next step in Syria is inextricably linked to the situation in Iran. The US government's biggest national security concern in the region is an Iranian regime with potential access to nuclear weapons. A nuclear Iran would destabilize the region, shock oil prices, and threaten US allies. Longer term, it's harder to map out the implications, but they aren't pretty. A nuclear Iran could trigger a domino effect among Middle Eastern countries; should another Arab Spring occur, a failed state with a nuclear weapons cache is a frightening prospect.Not intervening in Syria - letting Bashar Assad cross Obama's red line of using chemical weapons on civilians - makes any red lines regarding Iran's nuclear progress blurrier. In fact, by punting the decision to Congress and further complicating the causality between a broken red line and punishment, Obama may have already done just that.It's a quirk of history that Obama is in this position in the first place. When Obama originally set his red line back in August 2012, he caught his advisers completely off guard. As the New York Times reported in May: "Moving or using large quantities of chemical weapons would cross a 'red line' and 'change my calculus,' the president declared in response to a question at a news conference, to the surprise of some of the advisers who had attended the weekend meetings and wondered where the "red line" came from. With such an evocative phrase, the president had defined his policy in a way some advisers wish they could take back."If Obama set the red line without consulting his own staff, he certainly didn't ascertain whether other nations would also "change their calculus" in response to chemical weapons use. That helped lead to the embarrassment in Britain last week, when the House of Commons declined to join any potential American strike against Syria. This is possibly Obama's hardest-earned lesson of the Syria debate thus far: even if you feel the need to tout American exceptionalism, don't let it apply to your red lines. If you set a red line by yourself, be prepared to defend it alone as well.Let that be a lesson on Iran. With the recent IAEA report suggesting that Iran is inching ever closer towards nuclear breakout capacity, potential upcoming negotiations with Iran carry an even greater urgency than usual. And there are compelling reasons to be optimistic (or at least less pessimistic than usual): both parties have something that the other wants, and Iran has a new president.In June, Hassan Rouhani won the Iranian presidential election with an outright majority - as a centrist candidate with a platform of patching up relations with the West. Ahmadinejad's retirement is perhaps an even greater addition by subtraction. While it's important to remember that the buck stops with the Ayatollah, Rouhani's election could usher in a reset in negotiations, and perhaps a modest deal, likely in the form of inspections and a slowdown in enrichment in return for reduced economic sanctions.The United States needs to seize this chance. If negotiations fail, it could still prove difficult to maintain the current level of sanctions pressure for two reasons. First, because Iran now has a charismatic president instead of one who's easy to hate and speaks out against Israel. Second, Rouhani is bent on promoting transparency and efficiency in the Iranian domestic economy. This makes it more tempting for countries like China, India and Russia to strike deals with Iran -- even if it means bending the rules on sanctions. As the United States has witnessed in Syria, it's hard to hold the international community to a strict red line - especially when there are economic incentives to the contrary.So what's next in Syria? It's more likely than not that Congress will approve a limited military strike - and that the ensuing intervention will prove to be limited. If Congress rejects the president's call for a military strike, it will set a dangerous precedent on American red lines and undermine the United States' credibility in advance of possible talks. If Obama's proposal does pass and the US strikes, the administration must prepare for the risk that Iran will respond with escalatory asymmetric attacks, and it must ensure that any fallout from Syria does not scuttle upcoming nuclear negotiations.A few months from now, in all likelihood, the US will once again be on the sidelines in Syria, decrying continued violence with rhetoric but little action. Media attention will shift to the high stakes dynamics with Iran. It is, after all, where the US government has been focusing all along.