The nation's top narcotics control official told Congress Thursday that the nearly 1,800 pounds of fentanyl seized at the southern U.S. border since 2017 is one reason why President Trump's border wall will help tame the opioid crisis.

James W. Carroll Jr., director of the Office of National Drug Control Policy, also told the House Oversight Committee that U.S. Border Patrol agents, which are stationed between points of entry, have seized 6,500 pounds of cocaine in fiscal 2018 and 8,100 pounds of cocaine in the first five months of 2019.

"God bless the CBP [Customs and Border Protection]," said Carroll.

Rep. Debbie Wasserman Schultz, D-Fla., took issue with Carroll's numbers and said a wall would not stop drugs coming into her home state. She said Trump's decision to cite illegal drugs as a reason for the wall was an attempt to get additional border fencing from an unrelated health issue.

"He is planning to take millions of dollars from drug interdiction and drug forfeiture to pay for a border wall when he supposedly has declared a national health emergency related to the opioid crisis. Those are incongruous actions. How can they be justified?" she asked Carroll.

"I disagree with you that they are incongruous. I think they are totally related. What we are seeing are drugs coming across into this country through every method possible," he said.

Wasserman Schultz argued that 90 percent of the drugs that enter the U.S. come through lawful points of entry. But Carroll said that statistic only reflects seized drugs.

"Ma'am, 90 percent of the drugs that are captured — it's not 90 percent of the flow," Carroll said. "There's a big difference between what is captured and the flow of drugs."

And when Wasserman Schultz said a wall won't cut it, Carroll responded, "A wall will actually cut it."

The White House plans to use $6.6 billion of previously appropriated funding to build 234 miles of barrier along the southern border after Congress gave him $1.375 billion, roughly one-quarter of the $5.7 billion he requested in December.

Trump opted to claim $600 million from the Treasury Department's drug forfeiture fund, $2.5 billion from the Defense Department's drug interdiction program, and $3.5 billion from a military construction fund.