President Trump in Washington in October. (Nicholas Kamm/AFP/Getty Images)
Opinion writer

We already know President Trump is extraordinarily sensitive to the numbers of illegal immigrant crossings into the United States, seeing it as a metric that reflects his failure to control the border. When numbers have surged in the past, he has mercilessly berated top officials and, in recent days, he has threatened to slap tariffs on goods imported from Mexico to force that country to do more to stop the migrants that his “toughness” has failed to deter.

Now, the number of border crossings has spiked once again. The Post’s Nick Miroff reports:

The Central American migration boom that has swamped U.S. authorities grew even larger in May, according to U.S. Customs and Border Protection statistics released Wednesday that show more than 144,000 migrants were taken into custody, a 32 percent jump from April.

It was by far the largest one-month arrest total since President Trump took office, and it was the highest monthly figure in 13 years, CBP officials said Wednesday afternoon.

May was the third month in a row that border detentions topped 100,000, led by record-breaking levels of illegal crossings by Guatemalan and Honduran parents bringing children. CBP officials told reporters that agents and officers detained more than 100,000 family members and children, leaving holding cells “bursting at the seams.”

These spikes are not driven by the traditional type of migration — single adults looking to cross illegally. Instead, they are largely swelled by families and children who are fleeing terrible civil conditions at home and are looking to turn themselves in to exercise their legal right to apply for asylum in the United States.

The president’s threat of tariffs is meant to pressure Mexico into doing more to block these flows — by preventing them from entering Mexico from Northern Triangle countries, cracking down on smuggling networks, and keeping more asylum applicants in Mexico to prevent them from waiting in the United States. The Trump administration sees the primary problem as a “pull” factor — families want to apply for asylum and exploit court backlogs to melt into the interior while awaiting hearings, to which they won’t show up.

The administration wants Democrats to back legal changes allowing for the long-term detention of families, supposedly discouraging these migrations. But that’s a humanitarian nonstarter for Democrats, who have a completely different diagnosis of the problem, and Trump’s frustration has led to unhinged actions such as pressuring top officials to break the law by shutting out migrants entirely.

The latest of these unhinged things is the threat of tariffs against Mexico. But, now, Bloomberg reports that Senate Majority Leader Mitch McConnell (R-Ky.) has privately warned that Trump should hold off on the tariffs until he can personally appeal to Republicans, whose support, McConnell claims, cannot be taken for granted.

But there’s another thing about this situation that really needs more attention: Trump’s continued threat of tariffs to get Mexico to halt the asylum crisis comes even as he recently cut off the very aid to Northern Triangle countries that could go some way toward addressing that crisis.

In remarks on the Senate floor on Tuesday, Senate Minority Leader Charles E. Schumer (D-N.Y.) highlighted this. The administration has asked Congress for billions in additional money to deal with migrants, by funding more shelter capacity for children and detention beds.

During his remarks, Schumer noted that Senate Democrats recently rolled out their own comprehensive plan to deal with the asylum crisis, including by restoring aid to the Northern Triangle. Schumer vowed that if such a supplemental border funding bill comes up, they will try to attach those proposals to it, and if that fails, they’ll try to restore that funding to any future funding bills:

The solutions we proposed are the types we should debate. So we are going to push forward with these proposals. Democrats will seek to add these policies to any package of border legislation that comes here before the Senate.

And if no legislation dealing with the border comes up, Democrats will seek to add security assistance for Central American countries to an appropriations bill and push for language that requires the administration to use it.

Senate Republicans will, of course, block this, since Trump is raging at those other countries as well for supposedly sending us their migrants. But Democrats should continue highlighting this anyway.

“Democrats are right to demand aid to Central America,” Kerri Talbot, policy director at the Immigration Hub, told me. "We have to address the real reasons they are coming. This makes much more sense than hurting our economy by imposing tariffs — which will do nothing to curb migration.”

This dual response — threatening tariffs against Mexico to get it to do more to stop migrants, while also cutting off aid to the Northern Triangle to pressure those countries to stop imposing their migrants on us, rather than trying to improve the horrible conditions driving them — captures the follies here in a particularly glaring way.

Trump simply cannot understand these migrations as complex phenomena that require complex solutions aimed, at least in part, at mitigating their root causes. He only sees them as an effort by all these countries and migrants to scam us and rip us off, things that can only be solved through “toughness." No matter how many times this fails, the answer is always more toughness.

Read more:

Daniel W. Drezner: Trump thinks immigration is a winning issue for 2020. Is he right?

Robert J. Samuelson: There is a sheer nastiness to Trump’s Mexico tariffs

Marc A. Thiessen: Tariffs won’t solve our border crisis. But Democrats denied Trump the tools he needs.

Henry Olsen: Trump’s immigration plan has one key fault