Back in early March, President Trump was still downplaying the severity of the coronavirus threat. But there was one measure he hailed as being important to stop the spread: a border wall. “Going up fast,” Trump tweeted March 10. “We need the Wall more than ever!”

Later that same day, though, the director of the Centers for Disease Control and Prevention, Robert Redfield, offered a very different take on the efficacy of the wall. Asked whether anything in the CDC’s coronavirus guidelines indicated structural barriers “would be of any use in mitigating” the virus, Redfield responded, “Not that I’ve seen.”

Throughout his 2016 campaign and his presidency, harsh immigration measures have served as a security blanket for Trump. Immigration is an issue he has returned to over and over -- both for political advantage to rally his base and now to demonstrate action to combat a crisis. Despite the border wall’s apparently lack of utility for coronavirus mitigation, for instance, Trump has repeatedly pointed to it in coronavirus briefings. It happened again Monday when he encouraged Adm. Brett Giroir, assistant secretary for health at the Department of Health and Human Services, to provide an update on the construction of the wall.

And on Monday night, Trump took things to a perhaps predictable level, announcing that he would sign “an Executive Order to temporarily suspend immigration into the United States!”

The timing of the move is curious. While health officials have credited his Jan. 31 travel restrictions on China with helping to stem the early spread of the virus, the virus has already been spreading for three months now. The United States has more confirmed cases than any other country (with the caveat that China’s data are unreliable), which means that community spread is now clearly and overwhelmingly the biggest obstacle.

And even as Trump announces his most severe immigration restriction to date, he is on the other hand suggesting an easing of coronavirus-spurred restrictions in certain parts of the country, in the name of reopening the economy.

What’s more, there are already myriad travel restrictions in place, including from China, Europe and other hot spots for the virus. As The Post reported Monday night, the State Department a month ago canceled most routine overseas processing of visas and all processing of refugee resettlement requests. However, it did resume processing visas for seasonal guest workers, whose fate is now up in the air depending upon the actual details of the executive order.

While the practical impact of the new ban is yet to be determined, it can’t be ignored that it comes at a time when Trump’s lack of early action to combat the virus has dogged him. Facing such questions, Trump has repeatedly cast the Jan. 31 travel restrictions on China as a bold and courageous move, inflating the opposition to the move and ignoring that many other countries were taking similar measures at the time. But Trump has struggled to enunciate any major actions taken during February and early March, before he announced strict recommendations on March 16.

Announcing the immigration ban now allows Trump to again cite something he has done, whatever the ultimate efficacy of that something might be this late in the game. His press secretary on Monday issued a statement emphasizing the economic impacts of immigration rather than framing immigration as a public health threat.

“As President Trump has said, ‘Decades of record immigration have produced lower wages and higher unemployment for our citizens, especially for African-American and Latino workers,'” said Kayleigh McEnany in the statement. “At a time when Americans are looking to get back to work, action is necessary.”

It’s understandable why he would go there: Because this in some ways has been fruitful territory for him.

In the first week of his presidency, Trump announced a controversial travel ban on seven majority-Muslim countries -- a decision that caught officials off-guard and momentarily led to chaos at the nation’s airports. But while that ban has been much criticized for allegedly targeting Muslims -- a goal Trump was explicit about during the 2016 campaign, when he proposed a blanket ban on Muslim immigration -- Trump’s authority to institute it was later affirmed by the Supreme Court, in a 5 to 4 decision.

Trump used the moment to cast the ruling as a triumph over an incensed left and a skeptical media.

“This ruling is also a moment of profound vindication following months of hysterical commentary from the media and Democratic politicians who refuse to do what it takes to secure our border and our country,” Trump said.

(Trump also expanded the ban to other countries around the same time he announced the China restrictions. This caused another backlash from Democrats, which he and supporters have used to wrongly imply they opposed the China restrictions.)

Ditto Trump’s use of a national emergency declaration to build the border wall last year. The move was criticized even by some Republicans who supported the wall’s construction because, they and others argued, it amounted to an end-around that supplanted Congress’s authority to authorize such spending.

While the legal battle over that move continues, a divided Supreme Court in the summer of 2019 allowed the construction to continue. And again, Trump claimed a “Big WIN for Border Security and the Rule of Law!”

Although the two battles have resulted in legal victories for Trump, that doesn’t necessarily mean they have been political wins. Polls have shown that as many as two-thirds of Americans opposed the border wall national emergency, and the country has long been split on the travel ban. But when it comes to implementing his agenda, they have provided two signature moments that Trump can use to rally his base and point to progress on the issue he deployed more than any other during the 2016 campaign -- to rapturous applause at his rallies.

Given Trump’s history of inflating the opposition to his China travel restrictions, it’s not difficult to see how this will pan out in the days and weeks ahead. Opponents will raise the same objections they have been raising for three years. They will argue that the move is overzealous and substantively suspect when it comes to the actual fight against the coronavirus.

But for a president who has been criticized for doing so little, it will provide him grist for the political mill and something to hail as concrete action -- no matter, as with the wall, the actual efficacy of the move and whether the experts were even asking for it.

Philip Bump contributed to this report.