WASHINGTON (Reuters) – U.S. immigration authorities’ lack of progress in automating their systems is compromising border security, making it more difficult to process people seeking to get into the country, a report said on Tuesday.

“We may be admitting individuals who wish to do us harm, or who do not meet the requirements for a visa,” John Roth, the Inspector General for the Department of Homeland Security, told a Senate Homeland Security Committee hearing.

The report from Roth’s office, released on Tuesday, said immigration officials expect it will take $1 billion and another three years, 11 years into the effort, to move from a paper-based system to automated benefit processing.

U.S. lawmakers have been calling for a tighter visa system since the November Paris attacks and December San Bernardino shootings. In Paris, some of the militants were Europeans radicalized after visiting Syria, and a California attacker had been admitted on a fiance visa.

They want to ensure that potential militants cannot enter the United States under programs, such as the “visa waiver” granted citizens of most western countries.

Roth told the Senate Homeland Security Committee that workers processing millions of applications for immigrant benefits work with a system “more suited to an office environment from 1950 rather than 2016.”

He said some green cards and other immigration documents had been mailed to wrong addresses, or printed with incorrect names, which meant they could have fallen into the wrong hands.

The poor quality of electronic data that is kept makes it more difficult to engage in data matching, to root out fraud and identify security risks, Roth said.

Shipping, storing and handling over 20 million immigrant files costs more than $300 million a year, he added.

The report also said the EB-5 visa program, which admits investors who spend $500,000 or $1 million in the United States, depending on the area, may not be subject to close enough scrutiny to ensure Americans’ safety.

The current system also allows “known human traffickers” to use work and fiance visas to bring victims into the country, the report said.

Republican Senator Ron Johnson, the committee’s chairman, said the modernization was too slow and expensive. “It should not take years and years and billions and billions of dollars,” he said.

(Reporting by Patricia Zengerle; Editing by Marguerita Choy and Alan Crosby)