WASHINGTON — The United States needs to do more to strengthen the “weak link” in the chain of efforts to keep terrorists from successfully crossing international borders, a new report finds.

While domestic homeland security initiatives have improved the ability to detect terrorists trying to enter the United States, there are significant gaps in the ability of many foreign countries to prevent terrorists’ travel – and a lack of coordination among U.S. agencies charged with working with vulnerable countries such as Pakistan is only making that problem worse, says the U.S. Government Accountability Office.

The report by the GAO, Congress’ investigative arm, will be discussed Wednesday at a Senate Committee on Homeland Security and Governmental Affairs hearing on terrorists’ travel, one of a series of hearings examining homeland security issues 10 years after 9/11. The report was requested by U.S. Sen. Susan Collins, R-Maine, the committee’s top Republican, and U.S. Rep. John Tierney of Massachusetts, the top Democrat on the House Oversight and Government Reform Committee’s national security subcommittee, .

“The U.S. is spending billions of dollars to increase our security by preventing suspected terrorists from traveling to this country. We have improved our watch lists and how we verify documents, among other refinements,” Collins said Tuesday in a statement. “But as the GAO report shows, we must also rely on the systems of our partner countries, which are hamstrung by troubling gaps ranging from corruption to counterfeit documents to poor record keeping.”

The GAO found several major problems hindering foreign countries from helping the U.S. prevent terrorist travel, including: a lack of information sharing about terrorists; a lack of ability to combat  fraudulent travel documents; and weak passport security in general.

“Inhibiting the movement of terrorists across U.S. borders is a key part of the U.S. strategy for protecting the United States and its interests abroad,” the GAO report states. “Although agencies have implemented significant new domestic programs to prevent terrorists from entering the United States, events of the past few years demonstrate that the international travel system is only as secure as its weakest link.”

For instance, GAO found, Pakistan has a fingerprint database, but doesn’t share its data across all Pakistani law enforcement agencies.

The U.S. has tried to help foreign countries do a better job securing their borders.

In some cases, the U.S. has found success helping a foreign country shore up its defenses. In Paraguay, for instance, U.S. officials helped improve its passport and travel document system so that it employs more and better identifiers such as fingerprints, photographs and signatures, the GAO says.

But there is a lack of coordination across many U.S. agencies, from the State Department to the Department of Homeland Security. The GAO found that in Pakistan, the State Department and Department Homeland Security had planned separate training earlier this year for a Pakistani agency in preventing fraudulent travel documents – without knowing that they were duplicating efforts.

Collins said the report shows the U.S. must make strides in more efficiently providing help to other countries trying to do a better job securing their borders.

“GAO found a real lack of coordination and wasteful practices among the agencies working to improve the systems of foreign countries,” Collins said. “We need less duplication and better coordination.”

In addition to Pakistan, GAO investigators also traveled to Kenya, the Philippines and Thailand to study how the U.S. was aiding foreign governments in preventing terrorist travel.