Gregory Korte

USA TODAY

WASHINGTON — President Obama signed an executive order Saturday revoking a 20-year system of sanctions against Iran for pursuing a nuclear weapons program.

The executive order finds that Iran's compliance with an international nuclear agreement — as verified by the International Atomic Energy Agency Saturday — "marks a fundamental shift in circumstances with respect to Iran's nuclear program." The United States agreed to lift the sanctions as part of an international agreement requiring Iran to mothball its nuclear capabilities for a decade or more.

The most significant effect of the executive order is to free up Iranian assets held in the international financial system, estimated to be worth between $50 billion and $150 billion. Obama administration officials have said they believe the value is on the lower end of that spectrum, because of Iran's international debts and the amount of currency it needs to keep in foreign reserves.

Most of the sanctions relief applies to what are known as secondary sanctions — those against non-U.S. citizens doing business with Iran. Primary sanctions — those against U.S. citizens — remain in place.

But there are narrow exceptions. The Treasury Department grant waivers for Americans to import food, carpets and other floor coverings from Iran. And on Friday, Obama signed a presidential memorandum allowing the export of commercial passenger aircraft to Iran on a case by case basis.

Obama allows sale of aircraft to Iran as nuclear deal nears implementation

The Treasury Department also removed about 400 Iranians from its blocked persons list Saturday, unfreezing their assets and allowing them to do business with Americans.

Obama administration officials have stressed, however, that other U.S. sanctions against Iran will remain in place. "We will continue to target sanctionable activities … including those related to Iran’s support for terrorism, regional destabilization, human rights abuses, and ballistic missile development," Treasury Secretary Jacob Lew said Saturday.

House Speaker Paul Ryan, R-Wis, said Obama lifted sanctions "on the world’s leading state sponsor of terrorism," and noted that it comes weeks after an Iranian missile test and just days after Iran held 10 U.S. sailors who found themselves in Iranian waters.

The president had the authority to revoke the sanctions by executive order because they were imposed by executive order in the first place.

Beginning in 1995, Congress passed a series of laws authorizing sanctions but giving the president wide discretion in how to put them into place. Presidents Clinton, George W. Bush and Obama all signed executive orders ramping up those sanctions, which Obama aides credit with bringing Iran to the table for negotiations.

Obama's highly technical, eight-page executive order revokes four previous executive orders and amended a fifth. But eight other executive orders imposing other Iran sanctions remain in effect.