The Washington Post is warning all migrants in the Honduran ‘caravan’ that they may be criminally prosecuted for trying to evade border guards this weekend, even if they bring children with them for legal cover.

The threat came in a Thursday evening report on the contents of a leaked policy memo sent to Homeland security secretary Kirstjen Nielsen:

The nation’s top immigration and border officials are urging Homeland Security Secretary Kirstjen Nielsen to detain and prosecute all parents caught crossing the Mexican border illegally with their children, a stark change in policy that would result in the separation of families that until now have mostly been kept together. If approved, the zero-tolerance measure could split up thousands of families, although officials say they would not prosecute those who turn themselves in at legal ports of entry and claim asylum. More than 20,000 of the 30,000 migrants who sought asylum during the first quarter — the period from October-December — of the current fiscal year crossed the border illegally. … The memo sent to Nielsen on Monday — and signed by acting Director of Immigration and Customs Enforcement Thomas Homan, Director of Citizenship and Immigration Services L. Francis Cissna and Customs and Border Protection Commissioner Kevin K. McAleenan — said attempted crossings by parents with children increased to nearly 700 a day last week, the highest level since 2016. The officials predicted that the number will continue to rise if Nielsen does not act.

The memo recommends jailing all migrants who sneak across the border, but not the migrants who walk up to border posts to seek permission to file for amnesty, the Washington Post said.

The Post did not say if the leak was intended to deter migrants from crossing the border.

Under existing laws, the roughly 1,200 migrants in the so-called ‘caravan’ can walk past border guards to ask officers and Justice Department immigration judges for permission to file asylum claims in federal courts.

That screening process is tightly governed by existing laws and court precedents, which require only that migrants show a “credible fear” of persecution should they be denied asylum. The low threshold ensures that border officers and immigration judges can only reject migrant requests if the asylum claims are very weak.

But most young men and women usually try to evade guards by sneaking or smuggling themselves over the border, via dangerous and expensive routes. The DHS memo targets them — and may deter some of the ‘caravan’ migrants from sneaking across this weekend.

In contrast, most of the people who ask for asylum are parents bringing their children from Central America. If their “credible fear” asylum claim is allowed, they will file an asylum claim and are released into the United States.

The asylum-seeking migrants are released for several reasons.

First, the immigration-court system has become backlogged since 2011 with more than 700,000 other asylum applications. The first available court dates can be two or three years in the future. Second, Congress has funded only 40,520 detention spaces for migrants in 2018, ensuring there are no detention beds for most migrants. Most of the detention facilities are occupied by people who were caught trying to sneak across the border. The border jumpers are held until they are identified and processed, although some are also sent to jail. Third, a 1997 court settlement, dubbed the Flores settlement, says officials cannot hold migrants with children for more than 20 days.

Once the asylum-seeking migrants and their children are released, they are also allowed to apply for work permits, and the children are allowed into schools in blue-collar neighborhoods.

Many migrants rationally use these “catch and release” loopholes to work legally in the United States for a few years, and many of those migrants also walk away from their asylum claims to work as illegal immigrants.

In 2017, the migration numbers dropped when Trump was elected. But the numbers are rising again because Democrats and business-first Republicans in Congress have refused to change the border laws or beef up border defenses. In fact, more than 100,000 migrants have used the asylum loopholes to walk through the walls since Trump was inaugurated.

The Post cites American pro-migration activists who also use the migrants’ children as a tool to remove the threat of jail for the parents. “I think it’s absolutely wrenching psychologically and terrible for both the children and the parents,” said Philip Schrag, a left-wing lawyer, pro-migration activist and lecturer. “What are we doing to those children psychologically that will haunt us years down the road if they become Americans?”

However, Attorney General Jeff Sessions is taking a variety of steps to reverse former President Barack Obama’s loose-border policies. For example, Sessions said in an April 23 statement about the caravan migrants “these individuals—and their smugglers—have ignored the willingness of the Mexican government to allow them to stay in Mexico.

The emphasis on migrants’ refusal of asylum in Mexico may help U.S. immigration judges quickly reject migrants’ requests to file asylum claims. According to the relevant federal regulation, “an alien is considered to be firmly resettled if, prior to arrival in the United States, he entered into another nation with, or while in that nation received, an offer of permanent resident status, citizenship, or some other type of permanent resettlement.”

Mexico does offer and grant asylum to people from Central America.