To build long-term alliances, a country needs to build trust. We can't expect other countries to take up arms and share our burdens on the battlefield if we're greeting their civilians by slamming doors in their faces.

Yet that's exactly what Washington is doing.

Consider Poland. Its soldiers fight alongside Americans in Iraq, and we have no better friend economically or militarily in all of Europe. But when Poles attempt to come to the U.S. for a short visit, they too often run into a brick wall.

A Boston Globe story last year told of Maria Buczyk, who wanted to visit her 83-year-old mother in Chicago. Buczyk already had been turned down twice by the U.S. consulate when she applied for a guest visa. Officials apparently thought she planned to emigrate to the States. "It's not true. I just want a month with my mother," Buczyk told the paper when it caught up with her as she was making her third attempt to earn a visa.

Her story isn't unique. Travelers from other allies as far-flung as the Czech Republic and South Korea also have met roadblocks when they wanted to visit the United States. It's time to make such treatment a thing of the past by extending the Visa Waiver Program.

VWP allows nationals from selected countries to travel to the U.S. for tourism or business without a visa for up to 90 days. The program enhances security by setting common standards and promotes economic growth and cultural ties. But it's an underused asset, which is creating problems with countries that should be our closest allies.

The program helps to improve international security, because it requires countries to have biometric passports. This helps U.S. customs and law enforcement verify a person's identity and crack down on suspected terrorists.

But the program's too small. Only 27 countries participate, and some critical allies are stuck on the sidelines. That's usually because of a technicality -- if more than 3 percent of the people from a country have been turned down when applying for a visa, the country is ineligible for VWP. But that puts too much pressure on American consular officers, who have only seconds to decide whether an applicant deserves a visa.

U.S. allies are eager to be admitted into the VWP for both the economic benefits and the symbolic most-favored-nation status. Besides, by limiting the program, Washington creates a perception of unfairness and double standards. Whether we mean to or not, we're causing resentment.

Polish citizens, for example, wonder why they cannot travel freely to the United States (even though Poland sent several thousand troops to Iraq) while the French and Germans (who condemned the war) can travel here freely.

In the past year, Congress has considered legislation to admit Poland, South Korea and other U.S. allies to the VWP, but with no results. Fixing this problem requires permanent, decisive action -- a change in the visa waiver law.

If Congress would agree to waive the 3 percent requirement, we could swiftly add six countries to the VWP: South Korea, Poland, the Czech Republic, Hungary, the Slovak Republic and India. All are proven friends in the war on terrorism, with vibrant economies that contribute greatly to the rapidly growing global economy.

Young people in these countries want to come to the United States to visit Niagara Falls and get business training, not to settle. Admitting them would make America safer and promote economic growth and freedom.

Plus, there's little danger to expanding the VWP, since countries can be removed if they suddenly fail to qualify. This happened to Argentina in 2002 when an economic crisis led a high percentage of its nationals to overstay their 90-day limit.

There's a reason we call it the "Global" War on Terrorism. In order to win, the United States must work with allies around the world to defeat terrorists. A smarter Visa Waiver Program would help us do that -- and keep us from alienating friends.

James Carafano is a senior research fellow for defense and homeland security at The Heritage Foundation.