But for Iran, the nuclear deal — once it is fully implemented several months from now — would have sweeping benefits, giving it access to foreign investment, trade with oil-thirsty markets in Europe and Asia, and escrow accounts currently holding more than $100 billion from oil sales out of Tehran's reach.
Those benefits could help revive Iran's economy and ease pressure on the government's budget, both of which rely heavily on oil revenues. But the oil export restrictions would only be lifted after the International Atomic Energy Agency certifies that Iran has complied with certain commitments and that isn't expected to happen until late this year.
The agreement's annex spelling out sanctions relief also says that the United States could issue trading licenses to the foreign subsidiaries of U.S. corporations. The annex says that the foreign units would be allowed "to engage in activities with Iran that are consistent with" the nuclear agreement. A senior administration official said the language was consistent with what Treasury has used in the past, but former Treasury sanctions official Richard Nephew, now at Columbia University's Center on Global Energy Policy, said it signaled "an easing over the status quo."
"This little paragraph is a really big deal," said Elizabeth Rosenberg, a senior fellow at the Center for a New American Security who previously worked at the Treasury handling sanctions issues. Rosenberg said the clause could open the door to Iran for many U.S. multinationals.
Sanctions have been at the heart of the lengthy negotiations and are credited with bringing Iran to the negotiating table. There are U.S. sanctions dating from the 1990s, U.N. sanctions dating from 2006 and more recent European Union sanctions on everything from arms and energy to travel and finance.
While the deal would lift most U.N. and EU sanctions, the Obama administration said Tuesday that the restrictions on U.S. trade and investment would remain in effect with the exception of imports of food and carpets and the export of civilian aviation equipment, including passenger planes, for Iran's airline, which administration officials said had one of the world's worst safety records.
The exception for aviation equipment could be a major boost for Boeing. Boeing spokesman Charles Bickers said the company was still "reviewing the agreement" and would not comment.
However, the restrictions will likely leave U.S. oil and gas companies on the sidelines while European and Asian firms rush to invest in exploring in Iran, home to the world's fourth biggest proved reserves. Those firms will likely include those, such as the Italian oil giant ENI, Norway's Statoil and France's Total, that were working in Iran before sanctions were imposed.
"U.S. companies all understand that nothing is going to change soon," said Robert McNally, former national security adviser to President Bush and president of the Rapidan Group, a consulting firm. "Barring a political moderation in Tehran, it is very unlikely the politics will improve enough to allow U.S. oil companies to go back in."
The price of the benchmark West Texas Intermediate crude oil rose 70 cents to $52.90 on Tuesday, after sinking sharply last week in anticipation of an accord.
The opening of Iran's oil sector could further strain Tehran's relations in the Persian Gulf region because Iran will press other members of the Organization of the Petroleum Exporting Countries to cut output to make room for more Iranian exports. Saudi Arabia, the cartel's main swing producer, pumped record high volumes of crude oil last month and shows no sign of scaling back.
Relations between Iran and other gulf members of OPEC have already been strained because of Iran's support of fellow Shia in Yemen, Iraq and Syria. Sunni states, most notably Saudi Arabia, have backed rival groups in those countries.
"The Saudis show no sign of cutting to accommodate Iran," said McNally. He said that the OPEC meeting scheduled for Dec. 4 "will likely be consumed by the question of how to handle Iran's return. It's going to be a knock down drag out I expect."
Iran's oil minister has said that Iran could produce another million barrels a day within a few months. Edward Morse, chief of global commodities research at Citigroup, said that Iran could add no more than half a million barrels a day to world markets by the middle of next year. While modest compared to global oil consumption of more than 93 million barrels a day, the extra supply could help ease pressure on global prices.
One thing that could spur Iranian oil sales for a few weeks immediately after sanctions are lifted: Iran has 53.5 million barrels floating on 29 tankers looking for buyers, according to Ami Daniel, chief executive of a maritime data firm Windward.
While 80 percent of Iran's export dollars come from petroleum sales, carpets are one of its next most lucrative exports. It is difficult to pinpoint exactly how much money the country pulls in from these handicrafts, but an estimate from the Iran National Carpet Center said it was about $560 million per year in 2012.
Iranian carpet makers once counted the U.S. as the largest market for their handmade wares. Back in the first decade of the 2000s, an exemption in U.S. rules allowed for the importation of carpets and certain food products from Iran. However, new sanctions implemented in 2010 got rid of that exception.
Iran's carpet industry has struggled mightily since it lost access to the U.S. market, and so it will likely cheer the chance to compete again for American shoppers. In 2014, the U.S. imported some $780 million in wool floor coverings, according to the Commerce Department. India accounted for more than half of those dollars, followed by China, Pakistan and Turkey.
Iran and the United States are also the superpowers of the pistachio market, the world's largest producers with Turkey and China trailing well behind. Iranian sales of the nut to the United States and other developed countries have been hindered by sanctions. Prices of pistachios have been high in recent years, largely because of the sanctions. But they could come down — and hurt American farmers — as more Iranian pistachios hit the market.
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Washington Post staff writer Sarah Halzack contributed to this article.
