The president’s latest tweet, late on Sunday, in which he lauded General Kelly for “doing a great job at the border,” adding that numbers (presumably of illegal immigration) “are way down,” has become the subject of controversy on Twitter, with many trying to debunk the president’s claims.

Since his tweet, several individuals, as well as media publications, have jumped to debunk the president’s claims. To prove their point, critics cited data from a 2015 study by the Pew Research Center that shows that net immigration from Mexico had been down over the last decade.

However, the president’s claims on the subject may be true after all, based on Politifact analysis of other recent statements by him on the same subject. A month into his presidency, President Donald Trump had boasted that 40 percent decline in illegal immigration.

"In the first full month of my administration following the issuance of my executive orders, illegal immigration on our southern border fell by an unprecedented 40 percent," Trump said March 13.

Following up, speaking to supporters in Kentucky on March 20, Trump raised the figure to 60 percent and said: "A lot of them are coming in from the southern border. Since the day of my election, we've already cut illegal immigration at the southern border by 61 percent, think of that, 61 percent, and we haven't started."

Politifact ruled the statement as mostly true based on statistics released March 8 by Kelly that showed a 60 percent decline in illegal border crossings from November, when Trump got elected, to February. However, the publication also cites experts who suggest different reasons behind the decline.

"It is almost always necessary to look at trends over a longer period, usually at least six months, to get a better sense of changes… It seems likely that the numbers of border crossers will go back up again before long given that the human rights situation in Central America is still incredibly problematic, and Central American asylum seekers are one of the main sources of migration in recent years," Denise Gilman, director of the Immigration Clinic at the University of Texas School of Law told Politifact.

According to Gilman, one of the possible reasons behind the fall in numbers may be more stringent policing on the Mexican side of the border.