Following news that illegal border crossings dropped by more than 50 percent over the last three months, Acting Director of the U.S. Citizenship and Immigration Service Ken Cuccinelli appeared on "Fox & Friends" Tuesday to explain how it's being done.

"There's no one silver bullet. The president has literally thrown every domestic and international effort he can at this and it's paid off," Cuccinelli said. "We're down more than 50 percent since May, in just three months.

"And I should point out that in the last eight years, I think this is the only July-August period you can find where the numbers go down, instead of up... They went down 18,000 apprehensions, from 82 to 64,000... This is really a testament to the president's aggressiveness," he continued. "We have a long way to go. And with Congress back from vacation, they're the obvious people to really make long-term changes."

Cuccinelli addressed President Trump's proposed border wall and said the administration expects to add 500 miles of new barrier in 2020, using Defense Department funds and the process of eminent domain.

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"When the president finally came out on top [in] one of the lawsuits where you had people trying to stop his use of Defense Department money, that was about $2.5 billion," he said.

"To get up to 3.6 billion more dollars is a big, big deal. And we think it could push us almost up to 500 miles of new wall by the end of next year. We're really accelerating the expansion of the wall effort in part because now we have more dollars available. We also... have gotten some private property rights through eminent domain."

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Cuccinelli also criticized local officials who refuse to cooperate with the federal government on immigration issues and accused them of putting American citizens at risk.

"What do we get? We get rapists, murders, gang members who flourish here because supposed law enforcement officers won't protect their own communities and the surrounding communities by turning demonstrated criminals over to ICE to begin the deportation," he said.