By Ovunc Kutlu, Mustafa Keles, Betul Yuruk

NEW YORK

President Barack Obama has been criticized for Mideast policies that many claim have left Iran with increasing influence in the region.

After eight years in the White House, those polices, particularly the Iranian nuclear deal Obama considers to be a major part of his legacy, have come under scrutiny.

At the beginning of the Arab Spring near the end of 2010, hopes for democracy in the Middle East were curtailed by the Syrian civil war, Yemeni crisis and a coup in Egypt.

"Early in his administration, he failed to support the people of Iran in their revolt against their government’s oppression," Peter J. Wallison, a senior fellow at the Washington DC-based think tank American Enterprise Institute, told Anadolu Agency.

"That error foreshadowed all the errors that were to come," he said. "It’s safe to say that the world is in immeasurably worse condition after Obama’s eight years than it was before he assumed office."

Also joining the chorus of criticism is President-elect Donald Trump who claimed during a presidential debate last month that Iran has increased its influence in the Middle East during Obama's years in the Oval Office.

"Iran is taking over Iraq, something they've wanted to do forever, but we've made it so easy for them," he said. "Iran should write us a letter of thank you."

Zalmay Khalilzad, a former U.S. ambassador to Afghanistan, Iraq and the UN, noted in a March 2015 article for The National Interest magazine that Iran "moved quickly and decisively ... to fill the security vacuum" in Iraq, stating that there is "a significantly increased Iranian presence in Iraq and growing domination by Tehran over the Baghdad government."

In a separate article four months later, he said, "Iran is well on its way to achieving regional domination through its gains in Syria, Lebanon, Iraq and Yemen.

"The Obama administration hopes that the nuclear deal will moderate Iran’s regional policies," he added.

The concern about Iran’s ability to grow its influence is predicated on Tehran’s access to funds and investments not allowed under decades-long sanctions.

After the nuclear deal and removal of sanctions, Iran's struggling economy and energy sectors began to show progress.

Having the world's second largest oil reserves and the fourth biggest natural gas reserves, the easing of sanctions enabled Iran to significantly increase its crude oil production and exports. It also opened the country's untapped gas resources to foreign investment.

At the time the nuclear deal was signed in July 2015, Iran produced an average of 2.9 million barrels per day (bpd) of crude oil. That figure rose to 3.7 million bpd last month, according to OPEC's Monthly Oil Market reports. Tehran has said it wants to increase it further to pre-sanction levels of more than 4 million bpd.

Including its energy industry, approximately $250 billion of foreign investment is expected to flow into Iran, and more than 800 energy projects are estimated to be implemented in the next 20 years, according to the Economic and Trade Impact Analysis on Iran after Embargo report prepared in cooperation with the audit firm KPMG, Foreign Economic Relations Board (DEIK) and Turkish Exporters Assembly (TIM).

Some sectors in Iran, however, such as banking, law and bureaucracy, have been slow to adapt to the post-sanctions environment and regulations in those areas need to be expedited in order to attract foreign investors.

Iran has reintegrated into the Society for Worldwide Interbank Financial Telecommunication (SWIFT) system and has begun to access its overseas frozen assets that are estimated to be around $150 billion and expected to be gradually released in coming years.

Between $30 billion and $40 billion foreign direct investment is projected to soon flow into Iran annually, according to observers.

After sanctions were lifted, Germany, France, the United Kingdom, Russia, China and Japan led investment interests in Iran, in order to gain shares in the country's newly opened market.

But the biggest concern surrounding foreign investment is the uncertainty created by Trump, and whether he would scrap the nuclear deal after taking office early next year.

While campaigning for president, the Republican candidate described the nuclear deal as "one of the worst deals ever negotiated" and called it a "disaster".

His fellow Republicans also harshly criticized the Obama administration in 2015, claiming the deal increased Iran's political and economic influence in the Middle East, threatened Israel's security and worsened the U.S.'s relations with its long-time ally, Saudi Arabia.

The Obama administration indicated earlier this month that $50 billion worth of Iranian assets are to be unfrozen as a result of the nuclear agreement.

The Treasury Department announced in September that it granted licenses for aircraft companies Airbus and Boeing to sell planes -- a total of nearly 200 -- and help Iran’s aging air fleet.

Trump's policies toward Iran and the Middle East will be closely watched, and his stance on the nuclear deal will become much clearer after taking office.