WASHINGTON — The scuttling of a Dubai-owned company's bid to gain control of U.S. port operations is unlikely to trigger negative economic consequences unless it is followed by dramatic changes to the laws governing foreign investment in the United States, global trade experts said.

Imposing new restrictions on foreign company takeovers would shrink the field of potential investors on American soil and almost certainly lead to retaliatory actions by other nations, said Todd Malan, executive director of the Washington-based Organization for International Investment.

Malan, whose group represents overseas companies with operations in the United States, noted that the stakes are not small for Americans: they own $2.9 trillion worth of shares in foreign companies through mutual funds, pension funds and direct investments. Moreover, U.S. exports totaled $1.12 trillion in 2005, or roughly 10 percent of the country's gross domestic product, according to Commerce Department data.

Foreign direct investment in the United States exceeded $1.5 trillion in 2004. Of that, roughly two-thirds came from Europe, compared with $17.8 billion, or about 1 percent, from the Middle East.

Republican and Democratic lawmakers cited national security as their reason for defying President Bush and pushing to block the takeover of six ports around the country by Dubai Ports World, much as they did last summer in threatening to stop a China-owned oil company from acquiring Unocal Corp.

"A year from now we're all going to be embarrassed by this," said William Reinsch, a high-ranking Commerce Department official in the Clinton administration who is now president of the Washington-based National Foreign Trade Council.

On the other hand, critics who say Congress overreacted "might have a different appreciation of the ports deal if the various emirs of the United Arab Emirates were to be swept away by some sort of Islamic revolution," said John Pike, director of GlobalSecurity.org.

Outside experts said they fear that as a protectionist bandwagon gains momentum in Congress, the process by which the government has reviewed foreign investment for the past 30 years will become more politicized. There also are concerns that American businesses will increasingly seize on the new political environment to gain advantages against international rivals when investment proposals come before the federal Committee on Foreign Investment in the United States, or CFIUS.

The uncertainty stirred up by the scuttled Dubai Ports deal — including a bill in Congress that would shift control of CFIUS from the Treasury Department to the Homeland Security Department and another bill that would broaden the definition of "critical infrastructure" — has already soured some defense-sector deals, according to Brett Lambert, managing partner of the Densmore Group, a defense industry consultant.