A U.S.-built F-5 Tiger jet on display.
Iran has fallen behind in the global arms race, but the Iran nuclear deal has paved the way for the country to make up for lost time. Pictured: An American-made aircraft F5 is shown at Holy Defence Museum in Tehran, Sept. 23, 2015. Reuters/Raheb Homavandi

The economically crippling stranglehold that Western governments collectively imposed on Iran nearly four decades ago began to slowly loosen its grip this week, and the country has responded in part by dusting off its decades-old shopping list for advanced weaponry and other defense items it has been coveting but could not acquire. After agreeing to forfeit its nuclear enrichment program in exchange for the oppressive sanctions being lifted as part of the Iran nuclear deal, which supreme leader Ayatollah Ali Khamenei officially endorsed Wednesday, Iran is apparently looking to make up for lost time from a military standpoint.

“Iran is really falling behind the conventional arms race in the Persian Gulf; and when you look at its Arab neighbors, they are spending tens of billions of dollars on modern American and Western military equipment,” Alireza Nader, a senior international policy analyst with a focus on Iran at the Rand Corporation, a Washington, D.C.-based think tank, said.

The landmark agreement officially went into effect Sunday, and without a nuclear arsenal, the formerly alienated Middle East nation was prompted to take inventory of its ability to defend itself against perceived threats from regional neighbors such as Saudi Arabia and Israel, which has long considered Iran to be a terrorist state. Pushed by a combination of its own outdated military equipment and the formidable military buying power of its oil-rich Middle East rivals, analysts said Tehran is urgently plotting to upgrade and replace its own antiquated defense technology in favor of Russian- and Chinese-made military equipment by spending oil revenue that's been trapped in an assortment of banks worldwide for the last three years.

Iranian Military Expenditure Over Time | FindTheData

Iran’s Aging Technology

Since the economic sanctions against Iran were first put in place more than 35 years ago under the direction of former U.S. President Jimmy Carter, Tehran’s military has largely been in a downward spiral. Under the Iranian Shah, who led the Persian country before the Iranian Revolution in 1979, Tehran bought dozens of U.S. and Russian aircraft to counter Israel and Saudi Arabia's big defense spending.

At the time, the F-14 Tomcat, the F-5 Tiger and the F-4 Phantom were all state-of-the-art U.S. jet fighters. But after fresh military sanctions in 1984 that forbid countries from selling U.S. weapons to Iran, including replacement parts, maintenance and related training, the equipment previously purchased from the U.S. would slowly become inferior while the rest of the world seemingly beefed up their stockpiles.

Eventually, the jets became unusable. Likewise, Russian fighters bought by Iran just before the dissolution of the Soviet Union, including the MiG-29 and the Sukhoi Su-24 and Su-25, also became mostly obsolete because Russia was largely in disarray as it tried to reorganize after the Cold War.

Throughout the sanctions, which are being lifted methodically but for the time being prohibit Iran's financial institutions from accessing the international banking transfer system SWIFT, the country has been selling oil. However, revenue from those sales has not been flowing into Iran but was placed in escrow into foreign bank accounts around the world. Iran is expected to receive $100 billion that it could use to improve its defenses when allowed back into the SWIFT system. It was immediately unclear when SWIFT, a privately-held company based in Belgium, would grant Iran access.

Iranian Armed Forces Over Time | FindTheData

Seeking Sellers

Prior to the sanctions, Iran had looked to the U.S. and Russia for the bulk of its military equipment. And while it's anyone's guess where Iran will now turn to help bolster its defense systems, it is likely to remain a customer for Russia as well as a potential new supplier.

“Iran’s new sales will probably come from China and Russia. Those are the two countries with advanced militaries that are most willing to sell weapons to Iran,” Nader, of the Rand Corporation, said. "The Europeans are eager to trade with Iran, but I think given their alliance with the United States and their ties to Israel and Saudi Arabia and other countries in the region, they might be quite reluctant.”

It’s not yet known if European countries and their respective defense manufacturers are realistically looking at Iran as a potential market, although it can't be ruled out entirely. In 2006, Austria sold 800 sniper rifles to Tehran, while Germany has allowed Iranian defense manufacturers to build their own versions of the 1950s Heckler & Koch G3A4 battle rifle and the equally aging MG3 machine gun. Iran also possesses the French anti-tank missile system and two dozen Mirage F-1 fighter jets that it stole from Iraq during the first Gulf War in 1991. Both are likely now unusable.

So far, Iran has been negotiating a deal to buy the S-300 missile defense system, which Moscow and Tehran agreed upon years ago before Russia joined the U.S. in opposing Iran’s attempts to become a nuclear state. Similarly, China has made a deal that would see Iran give up the running of its biggest oil field for 20 years in exchange for 24 Chengdu J-10 fighter jets. There has been no final decision between Beijing and Tehran.

Oil And Defense

Weaponry may be at the top of Iran's post-sanctions wish list, but with the price of oil having fallen to $46.15 a barrel from nearly $100 about a year ago, Iran’s ambitions will likely be hurt severely. With that in mind, Iran will have to think carefully about what areas of defense it needs to improve on first, experts said.

Those options range from providing Hezbollah fighters, who are supporting Syrian President Bashar Assad in the Syrian civil war, to boosting aerospace efforts, including space-based platforms such as satellites, to advance its military into the 21st century, according to Ariel Cohen, senior fellow at the Atlantic Council, an international affairs think tank based in Washington, D.C.

“The low oil prices will hamper Iranian spending, so you are going to see them prioritize in certain areas,” he said.

The Geopolitics

Iran's regional neighbors, including Qatar, Saudi Arabia, the United Arab Emirates and Israel, have steadily increased their respective weapons arsenals while the Islamic Republic has been mired under strict economic sanctions for the past few years. In 2012, Saudi Arabia spent more than $30 billion on 84 F-15 fighter jets and upgrades on 70 more, underscoring how powerful its grip on the region is. Iran’s sworn enemy, Israel, continues to be funded in part by the Pentagon and has almost full access to anything the U.S. is manufacturing.

Despite the obvious need for Iran to bolster its defenses, it's yet to be seen how it will go about spending the cash. While $100 billion sounds like a lot of money, it's a lot less than what's been spent over the last few years by Iran's regional rivals, who aren't trying to modernize an entire military that has languished under the weight of sanctions.

“It’s been really years since Iran bought a major weapons system from a foreign supplier. When you look at its conventional forces overall -- its air force, its navy, its battle tanks -- they are really decades old, as well as Iran’s air defense,” Nader added. “So the country is anxious to update its equipment.”