Some border hawks contend that the “March for Migrants” caravan making its way toward the United States is the direct result of the failure of the United States to stop a previous caravan that came in April.

President Donald Trump took to Twitter on Thursday to threaten to close the U.S.-Mexican border and send the U.S. military to enforce it.

The rhetoric echoed Trump’s language in April. Although many participants dropped out along the way during that trip, hundreds of people defied Trump’s tough language and made it to the United States. Many claimed asylum, and whether they won it or not, they almost certainly ended up staying in the United States.

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Central Americans watched how that situation played out and drew the obvious conclusion, said Jessica Vaughan, director of policy studies at the Center for Immigration Studies (CIS).

“I’m surprised that it took so long to organize another caravan after what happened in the spring,” she told LifeZette. “We gave into that.”

William Gheen, founder of the hard-line Americans for Legal Immigration political action committee (ALIPAC), put it more bluntly.

“I don’t believe a word he [Trump] says … I don’t expect him to do anything,” he told LifeZette.

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A number of laws and court rulings make it difficult to stop illegal immigrants when they claim asylum — which is becoming increasingly common — or when they are children.

Faced with a Congress unwilling to act, Trump finds himself in essentially the same situation he was in during the April caravan. David Cross, a spokesman for Oregonians for Immigration Reform — which favors stricter enforcement — said he figured another caravan was inevitable.

“This idea that we’re going to close the border — there is no such thing as closing the border.”

“I just felt said,” he told LifeZette. “I don’t think there’s anything President Donald Trump can do to stop it the way laws are structured … Nobody should blame this on Trump.”

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But Cross added that Trump’s threat to close the border sounds like “rhetoric that’s going to be hard to follow through on.”

‘No Such Thing as Closing the Border’
Brandon Judd, president of the National Border Patrol Council, said he doubts that Trump’s calls to close the border are realistic.

“This idea that we’re going to close the border — there is no such thing as closing the border,” he said.

Any time Border Patrol officers arrest someone, a claim of asylum triggers a long process, Judd said.

“All someone has to do is set one foot in the United States, and we have to take them into custody,” he said.

Judd said the last caravan was a “complete and total fiasco.” More troubling, he said, is that career supervisors in the Department of Homeland Security (DHS) have given officers no new policies or strategies since then.

“They tested the resolve of the United States government … That emboldened the cartels.”

“Our swamp … has not been drained,” he said. “We have the same people running these agencies … The career people know all they have to do is wait out the political appointees.”

Judd said organizers of the April caravan closely studied the results. Americans felt the impact long before this current caravan formed, he added.

“They tested the resolve of the United States government … That emboldened the cartels,” he said. “We saw an explosion in border crossings.”

The impact has been reflected in illegal immigration statistics. In August, 20,727 unaccompanied children and children and adults traveling together came across the border illegally or were deemed “inadmissible” at border-crossing stations.

That was more than in any August during Barack Obama’s presidency. And Judd said the numbers for September, which have not yet been publicly released, were even higher.

Vaughn, the immigration think tank policy director, said the rising number of families traveling across the border points to the failure of the U.S. asylum system. She said it is relatively straightforward to arrest and deport a foreign adult traveling alone. Single adults can be detained even if they claim asylum, pending the outcome of their cases.

But Vaughan said a court ruling prevents the long-term detention of children, whether they have traveled alone or with their parents.

Sending Mexico a Message
The Trump administration attempted to solve that problem with the zero-tolerance policy, which called for criminal charges against illegal border crossers. But that required jailing them and separating them from children traveling with them, which produced a backlash.

Trump ended the policy in June. The result is that authorities must release the illegal immigrant families to await their asylum claims. Few ever end up getting deported.

Trump also deployed the National Guard, but many experts believe that has had a limited effect.

Vaughan said the most effective response to the current caravan would be to persuade Mexican authorities to prevent the travelers from entering their country. She said it would be “provocative” if Mexico were to issue temporary travel visas to the migrants.

Mexican officials Thursday agreed to ask U.N. officials to help evaluate asylum claims and accept non-Mexicans who break away from the caravan and make it into the United States.

Threatening to close the border is a “legitimate option” if Mexico does not follow through, Vaughan said.

“They have a lot to lose if they behave in a way that causes problems for us,” she said.

Another option, Vaughan said, is to take a much more skeptical view of asylum claims. Under international law, people fleeing persecution are supposed to ask for protection from the nearest safe country. For Central Americans, that would be Mexico.

Vaughan said the Trump administration could refuse to admit anyone seeking asylum who is not from Mexico.

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Alternatively, she said, the administration could reform the initial screening of asylum claims, which requires an officer to determine if the foreigner has demonstrated a “credible fear” of persecution if deported. Under Obama, some 90 percent of applicants cleared that initial hurdle. The current success rate is about 75 percent.

Since only about 20 percent of asylum seekers who make it to immigration court win their cases, it makes sense to train adjudicators to weed out a higher percentage on the front end, Vaughan said.

To ALIPAC’s Gheen, however, such explanations are excuses. He insisted Trump has all the authority he needs to enforce immigration laws but has continued Obama’s “catch-and-release” policies.

Gheen said Trump promised to stop the last caravan.

“That’s not what happened. The caravan pulled up … and Trump allowed that caravan in,” he said. “The buck stops with Trump. It’s on Trump. It’s on him.”