One of Obama's central arguments about Iran is falling apart

President Barack Obama has spent a lot of time assuring those who are concerned about the impending Iran nuclear deal that sanctions relief would be spent on growing its economy rather than ramping up its participation in regional conflicts.

That argument rests on shaky ground amid reports of Iran's tremendous financial investment to back its closest Arab ally.

Eli Lake reports that Iran is spending much more to support the embattled regime of Syrian dictator Bashar Assad than the Obama administration has ever acknowledged.

The UN special envoy for Syria estimates that Iran spends $6 billion per year supporting Assad's government, and other experts estimated that Iran spends much more than that.

"Nadim Shehadi, the director of the Fares Center for Eastern Mediterranean Studies at Tufts University, said his research shows that Iran spent between $14 and $15 billion in military and economic aid to the Damascus regime in 2012 and 2013, even though Iran's banks and businesses were cut off from the international financial system," Lake reports.

If some of these sanctions are lifted with a nuclear deal that's likely coming by June 30, that would give Iran even more money to support its interests in the region.

"The White House seems deeply convinced that the money Iran may get will go to help boost the Iranian economy instead of being used to support their regional interventions and initiatives," CEO of Foreign Policy David Rothkopf wrote recently. "The [Gulf officials] at Camp David did not share this view (nor do some senior former officials of the administration with whom I have spoken).

"For example, even if the Iranians got only $100 billion and used 90 percent to help the economy, the remaining $10 billion would have a potentially big impact in places like Syria, Iraq, and Yemen," Rothkopf wrote. "Further, no one among the regional experts with whom I have recently spoken felt that the Iranians would use a fraction as low as 10 percent of the monies in support of their regional policies."

Obama has assured Americans that Iran's military activities are low-cost and that money Iran will be able to bring in after sanctions are lifted would go toward shoring up its economy.

He told The Atlantic in an interview last month: "It is not a mathematical formula whereby [Iranian leaders] get a certain amount of sanctions relief and automatically they're causing more problems in the neighborhood. What makes that particularly important is, in the discussion with the GCC countries, we pointed out that the biggest vulnerabilities that they have to Iran, and the most effective destabilizing activities of the IRGC and [Iran's] Quds Force are actually low-cost."

Given the problems Assad is facing and the cost of running a multi-front proxy war, the argument that Iran's activities are low-cost is becoming much more difficult to make.

Earlier this month, Iranian President Hassan Rouhani said that he would back Assad's regime "until the end," and sources in Syria report that about 7,000 Iranian and Iraqi fighters have arrived over the past few weeks.

Iran's Shia theocracy is also allied the Shiite-led government in Iraq. Iran has been extending its influence in both countries as it seeks to become a major power in the Middle East, and outsized influence involves investment.

Eased economic sanctions would give Iran even more money to sink into its proxy wars in these countries. A nuclear deal that would lift some sanctions in exchange for Iran freezing its nuclear program could see Iran gaining hundreds of billions of dollars over several years.

Syria hikes monthly salaries for front-line army troops Where do they get the cash? http://t.co/hTCXMAD4HT

- Mike Doran (@Doranimated) June 9, 2015

Iran has been a major player in the fight against the Islamic State terror group (also known as ISIS, ISIL, and Deash) in Iraq and Syria. But Shia fighters trained and supported by Iran have not only been fighting ISIS, but also moderate and radical rebel groups in Syria that oppose Assad's regime.

Basically, Iran is playing on multiple sides of the larger conflict engulfing its neighbors.

Iran's staunch backing of Assad puts the US in an awkward spot as officials publicly insist that Assad must step aside but do little out of concerns about upsetting Iran at the nuclear table on in Iraq.

"The Syrian-American community asked the Obama administration for airstrikes on ISIS near Marea [in northern Syria] many months ago," Mohammed al-Ghanem, the senior political adviser for the Syrian American Council, told The Daily Beast recently. "We were rebuffed for the astounding reason that aiding the rebels in Aleppo would hurt Assad, which would anger the Iranians, who might then turn up the heat on US troops in Iraq."

The same goes for Iranian-backed militias accused of killing Sunni civilians and burning down villages in Iraq as US warplanes support them against ISIS from the air.

Someone has to pay for all of the barrel bombs that Syrian warplanes are dropping on civilian areas as well as the array of weapons used by Shia proxies in Syria, Iraq, Yemen.

And even America's top military official believes that Iran would be happy to continue footing the bill with a fresh infusion of cash.

"If the deal is reached and results in sanctions relief, which results in more economic power and more purchasing power for the Iranian regime, it's my expectation that it's not all going to flow into the economy to improve the lot of the average Iranian citizen," Joint Chiefs of Staff Chairman General Martin Dempsey, said Tuesday in Jerusalem. "I think they will invest in their surrogates. I think they will invest in additional military capability."