The Mullahs in Iran have reason to celebrate.
After 36 years, Iran has reclaimed its role as the definitive power in the Middle East, a truism it has known all along since regional geopolitics changed as a result of the 1991 Iraq War.
The Islamic Republic has weathered the 1979 U.S. Embassy hostage crisis, a debilitating 1980-1988 war with neighbor Iraq, a large U.S. military presence in Kuwait, Saudi Arabia and Bahrain, constant war-mongering from Israel, UN sanctions and arms embargo, and enmity from some of its Arab adversaries in the region.
Through careful calculation -- and watching as its biggest regional rivals imploded -- Iran forced the U.S. to the negotiating table, a key demand it has reiterated for several decades on the basis of what it calls mutual respect.
It has also in this time successfully dominated Lebanon through its Hezbollah proxy and managed to maintain a lifeline to another -- Syrian Bashar Al Assad.
In Iraq, it has the Bush administration to thank for removing an arch-enemy -- Saddam Hussein and the Baathists -- and the Obama administration to praise for running from Iraq at just the right time, thereby ensuring that its progeny, the Dawa party (represented by Iraqi Prime Ministers Ibrahim Jaafari, Nour Al Malki, and Haider Abadi), continues to run Baghdad.
While the Islamic State in Iraq and the Levant threatens much of Iraq, Syria and other countries in the region, Iran has slowly occupied much of the center and south of the country to protect sacred Islamic sites in Najaf and Karbala, revered by Sunnis and considered sacrosanct by the Shia.
Its special forces and pro-Iranian militia have not only proven themselves as likely the only counter-force to ISIL but have started to dominate internal Iraqi politics -- they are given a near carte blanche to act with impunity.
With much of Iraq under its control (the rest of the country is under ISIL dominance), Iran has reach into Syria; it has funneled weapons, materiel and financial assistance to the Assad government.
Many pro-Iranian Shia youth in Iraq have also volunteered to fight along Assad's forces. Every week or so, an Iraqi family buries a "mujahid" who was killed fighting Sunni anti-Assad forces. Now, these youth are in some cases returning to Iraq to continue their jihad there.
Territorial and political influence aside, Iran's economy (and therefore its stature in the region) is expected to be given a significant boost as Tehran begins to pump and sell major quantities of oil.
With UN sanctions removed, Iran is likely to regain advantage within the powerful OPEC oil cartel.
Ahead of the OPEC Summit last June, Tehran oil officials said they are prepared to add an additional 1 million barrels to their national output within six months.
Iranian Oil Minister Bijan Namdar Zanganeh had said at the time that OPEC "needs to open space" for his country's anticipated boost in output.
This is also likely to pit Iran in a conflicting posture with Saudi Arabia.
But this isn't the only reason that Saudi Arabia joins Israel in warning that the P5+1 nuclear deal reached in Vienna is a "dangerous" blunder.
Iran and Saudi Arabia are engaged in what amounts to a proxy war in Yemen. Riyadh has accused Tehran of supporting and arming the Houthi rebels who began a sweep of Yemen last year.
In March, U.S. Secretary of State John Kerry toured the Arab countries of the Persian Gulf, including Saudi Arabia, to assuage fears that Iran will become more difficult to deal with following the signing of a deal.
Saudi Arabia has led a chorus of criticism against the White House's plans to reach a deal with Iran over the latter's nuclear program, believed by some -- such as Israel -- of being dangerously close to weaponization.
Kerry is hoping to convince Arab leaders that Iran would not be a threat should it be allowed to keep some of its enriched uranium.
When Saudi Arabia led an Arab coalition in bombing the Houthis in Yemen, Arab and global media questioned the logic of such a military campaign.
The Saudis knew that the U.S. and Iran would eventually reach a deal and therefore Riyadh acted preemptively.
Most analysts now predict that the war in Yemen will intensify in the months ahead.