Although performance metrics are still lacking for determining the effectiveness of specific types of investments in border security, history has shown that a mix of technology, physical infrastructure and personnel are effective in curbing illegal border activity, a senior Customs and Border Protection (CBP) official said last week.

“We know over the history of CBP and the use of barriers along the border as relates to wall, as it relates to the right mix of technology, infrastructure and people, when we apply those investments in a strategic way along parts of the border, we know that’s going to have a beneficial outcome,” Ronald Vitiello, acting Deputy Commissioner of CBP, told the House Homeland Security Subcommittee on Border and Maritime Security during a March 15 hearing to discuss the Trump administration’s 10-year, $33 billion proposal for border security.

Vitiello said that the deployments of physical barriers, technology and people lead to reduced illegal activity and increased public safety along the border.

What CBP currently lacks, as was the case under the Obama and Bush administrations, are solid performance metrics to better guide its investments in border security.

Rebecca Gambler, the director of Homeland Security and Justice at the Government Accountability Office, told the panel that based on her agency’s previous and ongoing work, CBP lacks the metrics to assess the contributions of its different investments to strengthen border security.

Rep. Luis Correa (D-Calif.) said without those metrics CBP’s decisions on where to invest resources aren’t being optimized. Correa pressed for when performance metrics will be available and Vitiello replied that there is no hard date but will probably be a year or so.

Vitiello agreed with Gambler and said the Department of Homeland Security (DHS) is directing that performance metrics be developed.

“We’re looking at giving you a better history of what’s happening, what has happened, and which of the investments are most appropriate, but I can tell you that if you don’t do all three of these things in simultaneous fashion, that you will not be as successful,” Vitiello told Correa.

The Trump administration earlier this year said it would cost about $33 billion over 10 years to deploy and maintain its proposed investment in physical barriers and related infrastructure, technology and personnel. Of that amount, $18 billion is proposed for new and replacement walls.

Reps. Michael McCaul (R-Texas) and Bob Goodlatte (R-Va.), the chairmen of the House Homeland Security and Judiciary Committees, respectively, in January introduced the Securing America’s Future Act (H.R. 4760), which would authorize $38 billion for border security over 10 years. The bill calls for spending for additional wall and related infrastructure along the southern U.S. border, investments in technology, including a biometric entry and exit solution at U.S. ports of entry, and additional personnel.

Claire Grady, undersecretary of Management at DHS, told the panel that the cost estimates in the bill “align” with the estimates DHS has done. She added, though, that there are still additional personnel and sustainment costs related to the various investments in border security that stretch beyond 10 years.

Vitiello said CBP’s plan for physical barriers includes 316 miles of new pedestrian fencing, which would be in addition to 654 miles of existing fencing and wall structures erected during the Bush and Obama administrations, and another 272 miles of secondary barriers. Where new barriers are proposed, CBP plans to also install fiber optic cabling that senses local seismic activity as well as nearby digging by people. The fiber optic sensor will alert a control center so that agents can be directed to check on the activity, he added.