For more than a year, the debate over whether the U.S. should export some of its natural-gas bonanza has centered on how exports could affect the U.S. economy and manufacturing.

Increasingly, though, the geopolitical implications of exporting U.S. gas are shaping the debate, with proponents optimistic that the potential dividends for U.S. national security could tip the scales in their favor.

Proponents of U.S. gas exports, including current and former lawmakers, say that exporting some U.S. gas would bolster America's relations with allies in Europe and Asia, weaken the hold of major energy producers such as Russia and help further isolate Iran. Critics worry any strategic advantage would be outweighed by eroding the benefit cheap energy offers U.S. industry at home.

Lawmakers on the House Energy and Commerce Committee's energy and power subcommittee will examine the "direct political implications" of the U.S. gas boom at a hearing Tuesday.

"Opening trade in natural gas with our closest allies is clearly in the national security interest of the United States," said former Sen. Richard Lugar (R., Ind.), who championed the idea of exporting gas to North Atlantic Treaty Organization allies before leaving the Senate after the 2012 election.

The wrangling over how best to take advantage of U.S. energy resources reflects a huge shift. Since the 1970s, U.S. dependence on foreign energy suppliers constrained its foreign policy. Today, proponents of strategic exports believe the U.S. could turn energy to its advantage.

The U.S. gas boom is already having an impact on global energy relations, even before the U.S. has exported any significant amount. Liquefied natural gas from the Middle East once meant for the U.S. has been diverted to Europe instead, freeing countries there to renegotiate onerous gas contracts with Russia.

The prospect of significant volumes of U.S. gas flowing onto the world market has U.S. allies clamoring for access.

"New flow of LNG supply from the U.S. to Asia is an essential game changer that would contribute to energy security as well as economic and geopolitical stability in Asia," said Toshimitsu Motegi, Japan's minister of economy, trade and industry, in a speech Friday in Washington, D.C. He said he hoped approval of gas exports to Japan would be the first order of business for Ernest Moniz, who is awaiting Senate confirmation as secretary of energy.

India's ambassador to the U.S. has publicly pleaded for U.S. gas as a way to get cleaner-burning fuel. Companies from the U.K., Spain, South Korea and India have signed preliminary contracts to import gas from the U.S. if the government approves export projects. Even countries such as Germany, which have traditionally relied on Russia for gas, have told U.S. lawmakers they are interested in access.

Some 20 export projects are awaiting approval by the Department of Energy, which has to approve deals with countries with whom the U.S. doesn't have a free-trade agreement. The Department of Energy hasn't given a decision date, but a department official told Congress in late April that decisions could come in a matter of weeks.

Some powerful groups are skeptical of the merits of sending big volumes of U.S. gas overseas. Dow Chemical Co. (DOW) helped form a coalition of energy-intensive companies that say that shipping gas abroad could raise prices for gas at home, undermining a competitive advantage.

"We could make a very strong case that we could maintain or drive United States influence through an increasingly strong, robust U.S. economy that is exporting more goods overseas" instead of shipping raw materials, said Kevin Kolevar, vice president for government affairs at Dow.

Proponents of gas as a geopolitical weapon have proposed legislation that would expedite export approvals for NATO allies and Japan. Exporting gas "is an opportunity to strengthen our economy and strengthen our hand in the world," said Rep. Tim Ryan (D., Ohio), a co-sponsor of a House bill.

However, legislation automatically granting export approval to certain countries could diminish the appeal of formal U.S. trade agreements and might "remove valuable U.S. leverage in international trade negotiations," said Michael Levi of the Council on Foreign Relations in House testimony last month.

Even China, whose demand for natural gas is expected to soar in coming decades, could be a market for U.S. gas exports, proponents say. That would help improve the U.S. trade balance and help China address pollution caused in part by reliance on burning coal, they say.

"It would also put us in a better place when we go to do various negotiations with the Chinese, whether that's on issues such as North Korea or others," said Rep. Mike Pompeo (R., Kan.), a co-sponsor of the House legislation who said he would raise those issues at Tuesday's hearing.

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