Story highlights The impact of the current fence along the U.S.- Mexico border is unknown, a government study found.

The fence has been breached more than 9,200 times in roughly five years.

(CNN) While President Trump and government officials develop plans for a "wall" between the U.S. and Mexico, the agency responsible for securing the border is uncertain how successful the current fence has been.

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.

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