MEXICO CITY — Here in Mexico, as around the world, we are haunted by the wrenching image of Óscar Alberto Martínez Ramírez, 25, and his 23-month-old daughter, Valeria, nestled together on the bank of the Rio Grande after they drowned in the river near the international bridge to Texas. This tragedy shines an unforgiving light on the President Trump’s crackdown on legal asylum claims at the border.

These deaths, the more than two dozen others who have died in Immigration and Customs Enforcement custody since 2017, and the suffering of countless families, are the direct result of strategic policy choices — from increasing criminal prosecutions of people who illegally cross the border to shutting down legal points of entry and limiting asylum claims.

But Mr. Trump’s policies aren’t just cruel: They simply do not work.

Envisioned as a deterrent, these policies had the opposite effect. In May, about 133,000 migrants were apprehended at the border, a 32 percent increase from April. Experts argue Central Americans are rushing north because they are worried they will miss their opportunity to reach the United States as the Trump administration militarizes the border and removes legal pathways for asylum seekers. June did have a decrease in apprehensions because of increased enforcement in Mexico. But the immense efforts taken by my country have merely returned migration figures to levels that remain among decade-long highs.

These policies fail exactly because they ignore the root causes of mass migration from Central America: failing economies, extreme violence, poverty, food insecurity and the collapse of democratic governance in the Northern Triangle countries of Guatemala, Honduras and El Salvador. Those countries have among the highest rates of homicide in the world, fueled at least partly by the United States’ insatiable demand for drugs.