President Donald Trump slammed the nation's immigration laws on Thursday and said that women were being raped "at levels that nobody has ever seen before" in a caravan of migrants traveling from Central America to seek asylum in the United States.

"Yesterday, it came out where this journey coming up, women are raped at levels that nobody has ever seen before," Trump told a roundtable on tax reform at the White Sulphur Springs Civic Center in West Virginia.

The president did not explain his remarks further, only saying: "They don't want to mention that. So, we have to change our laws."

In his overall attack on U.S. immigration laws, Trump also claimed that foreign countries were "not putting their good ones" in the visa lottery, citing the speech that kicked off his presidential campaign in 2015.

"Remember my opening remarks, at Trump Tower when I opened," he said. "Everybody said, 'Oh, he was so tough.' And I used the word 'rape.'"

Since the weekend, Trump has repeatedly bashed the migrant caravan, sponsored by People Without Borders, that had been traveling from Honduras through Mexico to seek asylum in the U.S.

Trump also threatened to kill the North American Free-Trade Agreement if Mexico did not stop the migrants.

Organizers abandoned the caravan in Mexico Wednesday — after Mexican officials returned many to Central America and following U.S. Homeland Security Secretary Kirstjen Nielsen’s announcement that Trump had ordered National Guard troops to the southern U.S. border.

Caravan leaders said most of the group would remain in Mexico, where authorities were working with individual migrants and families to get them temporary papers.

The group was organized to protect migrants from smugglers and crime cartels throughout Central America.

"All they want is a place to live in peace, where they can work without having guns pointed at them, without being forced to join a gang," said Irineo Mujica, head of People Without Borders.

A small number of migrants with strong claims for asylum would continue to the U.S. border on their own, he said.

President Trump referenced Mexico's efforts to stop the caravan in West Virginia.

"Mexico's been pretty good," he said. "They were very good to us yesterday, because they had the caravan of thousands of people coming up from Honduras.

"Thousands of people.

"Mexico has very tough policies" on immigration, Trump later said. "They can do whatever they want — which is the way it should be, to be honest.

"You're violating something very sacred," he said. "You're violating a border."

Later, Trump told reporters aboard Air Force One that he was considering sending 2,000 to 4,000 National Guard troops to the border, offering the first potential details about the size of the move since publicly raising the idea — which has been embraced by previous presidents, including George W. Bush and Barack Obama — on Tuesday, and signing a proclamation officially directing it the following day.

Trump also hammered California, which has sued the federal government dozens of times since he took office, on issues ranging from voting rights to immigration.

"In many places, like California, the same person votes many times," he said. "They always like to say, 'Oh, that's a conspiracy theory.' Not a conspiracy theory, folks. Millions and millions of people."