Donald Trump had sent a bold message to his successor just before the former president visited the U.S.–Mexico border: “For the sake of our country, Joe Biden must finish sealing the border immediately, or the American People must elect a Congress that will.”

In a rare opinion article written and published in Washington Times on Wednesday, June 30, Trump lamented that he helped build a border wall to protect the country, but “Biden sabotaged the completion of the wall.”

“Biden has enacted the most radical open borders agenda imaginable. This is perhaps the first time in world history a nation has purposely and systematically dismantled its own defenses to invite millions of foreign migrants to enter its territory and break its laws,” Trump wrote.

“No one knows who they are, presenting a dangerous threat to Americans. To say that Biden has provoked a national security disaster does not even begin to do justice to the calamity,” he added.

The former president pointed to the number of migrant arrests at the southern border to back his claims. In May, illegal border crossings were nearly 700% higher than the same period last year when Trump was still in office. More unaccompanied minors have arrived for each of the last three months than in any prior month in recorded history. Seizures of fentanyl increased 265% from last year.

By restoring the catch-and-release program, Biden has “torn up our hard-earned asylum agreements with Mexico, Guatemala, Honduras, and El Salvador, and announced that anyone on the planet who lives in a crime-afflicted area now qualifies for asylum in the United States.”

Meanwhile, U.S. Immigration and Customs Enforcement are effectively shut down, senior border security officials have been fired, and criminals are being released in record numbers.

But to top it all off, Trump said, Biden has announced a new program whereby the U.S. government will literally pay to fly illegal aliens’ relatives from other countries to join them in the United States.

According to the former president, those policies are utterly depraved, which would completely abolish America’s southern border.

“Yet of all the vindictive, shocking, and self-defeating border security actions Joe Biden has taken, none surpasses his decision to stop the final completion of the wall,” Trump wrote.

Trump cited Customs and Border Protection data, saying that nearly 740 miles of a border wall had been fully funded. More than 660 miles were already built or undergoing construction before he left office, with a few key areas remained to be completed. Still, Biden ordered an immediate halt to constructing the wall on his first day in office and impounded the funds Congress had appropriated.

“By stopping construction, Joe Biden purposely and deliberately left gaps in the wall, creating unsealed channels right in the middle of the border to be exploited by human traffickers and drug smugglers,” Trump declared. “I built a wall—Biden built a humanitarian catastrophe.”

Trump affirmed that the border wall he built effectively works. After the border wall was constructed, illegal border crossings dropped by 90% in the Yuma area and 80% in the Rio Grande Valley and parts of El Paso. Illegal drug trafficking and human smuggling drastically decreased in those areas.

Trump claimed that though Texas now says they will build its own wall, but “this should not be necessary and is at best a band-aid over the gaping wound Biden created.”

“Border security is a core responsibility of the federal government,” Trump declared, so governors and state legislatures should certainly do what they can—but there is no substitute for federal action.

“We handed Biden the most secure border in history. We ended asylum fraud, terminated catch and release, negotiated historic migration agreements with Mexico and other countries, and virtually stopped illegal immigration. Precisely because of these policies, we achieved an incredible 90% reduction in illegal crossings,” he wrote.

“The United States must immediately restore the entire set of border security and immigration enforcement measures we put into place — and critically, we must finish the wall,” Trump urged.

The 45th president of the United States then concluded: “A nation without borders is not a nation at all. For the sake of our country, Joe Biden must finish sealing the border immediately, or the American People must elect a Congress that will.”

Trump’s opinion article was released hours before he traveled to the U.S.–Mexico border later on Wednesday with Texas Gov. Greg Abbott to tour the “unfinished border wall.”