Government watchdogs have found that thousands of people who shouldn't have been admitted to the United States were mistakenly allowed in last year because of security lapses at legal border crossings.
The number of inadmissible aliens who managed to enter through official ports of entry in 2006 was not disclosed in Monday's report from the Government Accountability Office.
However, a source who has seen a full version of the report, in which those statistics were included, put the total at 21,000.
The author of the GAO report, Richard Stana, said most of those who were wrongly allowed to enter were economic migrants who did not present a security risk.
"But as we saw in the recent past, it doesn't take too many people getting through the ports of entry to cause some real trouble," he said. "And not everyone who comes in and is a danger needs to be a terrorist. It could be someone connected with a criminal enterprise."
Understaffing and turnover at Customs and Border Protection, the agency that oversees the nation's 326 land, sea and air ports of entry, has contributed to the problem, according to the GAO report. However, investigators also cited weak management controls and complacency and inattentiveness by some officers.
GAO investigators arriving at one point of entry found no border agents in the inspection booth, while at other locations, agents didn't ask for travel documents, according to the report.
"Supervisors aren't demanding that the agents do their jobs and ask the right questions and look at the right documents," Stana said. "It's because they can't get people trained properly, and it's because staffing is short."
The Customs and Border Protection's stance is that at busy border crossings, it has to balance security with commerce.
As a result of its own earlier investigations, Customs and Border Protection issued new policies and procedures to tighten security at ports of entry, but, months later, GAO inspectors found that many of the same weaknesses persisted.
In July, Customs and Border Protection issued new procedures for conducting inspections at border crossings. However, GAO investigators concluded the agency has not put the management structure in place to make sure those procedures are consistently implemented at all of the crossings.
Monday's report "confirms that Customs and Border Protection must do a better job of recruiting new officers and retaining and training those already on the job," said Democratic Rep. Bennie Thompson of Mississippi, the chairman of the House Homeland Security Committee.
"Employee retention and recruitment problems at CBP may be indicative of larger morale and vacancy problems at the Department (of Homeland Security), but that's no excuse," he said in a statement. "While this administration pumps millions of dollars into hundreds of miles of real and virtual fences, it must not ignore critical vulnerabilities at our ports of entry."
The National Treasury Employees Union, which represents 17,600 Customs and Border Protection officers manning ports of entry, said the agency is understaffed and poorly managed and officers are overworked and not adequately trained.
About 400 million people enter the U.S. through legal checkpoints every year, according to The Associated Press.
"It is clear that CBP needs thousands more front-line employees, not just to do the job the nation has a right to expect but to provide enough manpower to staff ports of entry while critically necessary training is provided," said Colleen Kelley, the union's president, in a statement.
