The 654 miles of fence already lining the border have been breached more than 9,200 times between roughly 2010 and 2015, according to a report released Thursday by the Government Accountability Office (GAO)
, citing records from the U.S. Customs and Border Protection (CBP).
The GAO report does not conclude fencing has proved ineffective — rather, it states CBP has not implemented a way to measure the effectiveness of the current fence on slowing down illegal entries.
CBP officials say efforts to measure the effectiveness of fencing were stopped in 2013 due to "funding shortfalls," according to the report.
Border Patrol officials interviewed by the GAO said fencing helps divert illegal border-crossings away from urban areas and into rural areas where agents can more readily respond. But officials also said smugglers and others can breach border fences by simply cutting through or finding ways over or under them.
In response to GAO's findings, the Department of Homeland Security said metrics to assess fencing contributions would be developed, according to the report.
The CBP acknowledged the GAO report, and said it would be implementing its recommendations.
"As a result of CBP's tactical infrastructure and technology investments between the ports of entry, the U.S. Border Patrol (USBP) can detect and interdict illegal activity, monitor evolving threat patterns, and strategically deploy assets," a spokesman said.
The Department of Homeland Security is weighing various options for wall construction or additional fencing on the border. DHS Secretary John Kelly is expected to present a proposal to President Trump, and the administration could then present a plan to Congress.
As CNN reported Thursday
, sources involved in high-level discussions with DHS are set to recommend the construction of additional fencing rather than a concrete wall, as President Trump called for during the campaign.
Just hours before the GAO released its report Thursday, border security officials testified on Capitol Hill about the ongoing threat of drug cartels and their ability to breach security layers along the southwest border.
Matt Allen, an assistant director for DHS investigations, testified that cartel smugglers can sidestep fencing by launching drugs over the border with air or propane cannons or by using vehicle "drive-throughs," where ramps and even cranes lift vehicles over barriers.
Paul Beeson, CBP's Director of Joint Task Force -- West, said fencing and surveillance technology have helped reduce these vehicle breaches. But he said these tools require support from border agents on the ground.
Possible unintended consequences of additional border barriers were also brought up at the hearing. U.S. Coast Guard Vice Admiral Charles Ray said a wall constructed along the border could in turn increase illegal border activity at sea.
"When determined illegal traffickers meet a hard barrier on the land, there is a percentage of them that will go to sea," Ray said.