Social media users believe they've spotted a glaring flaw in President Donald Trump's latest brainwave to paint the U.S.-Mexico border black to prevent people from scaling it.

Department of Homeland Security Secretary Krsti Noem confirmed on Tuesday (August 20) the 3,145-kilometre southern border wall, which she acknowledged was already "very, very difficult to climb," would receive the paint treatment to make the surface hotter to the touch.

The apparently foolproof logic behind this scheme is that, as black soaks up more heat than other colours by capturing nearly all wavelengths of light, nobody will dare attempt to scale the blistering hot surface.

"It's tall, which makes it very, very difficult to climb, almost impossible. It also goes deep into the ground, which would make it very difficult, if not impossible, to dig under," Secretary Noem explained.

"And today we are also going to be painting it black. That is specifically at the request of the president, who understands that in the hot temperatures down here, when something is painted black, it gets even warmer, and it will make it even harder for people to climb.", reports the Mirror US.

U.S. Customs and Border Protection's recent figures show that southern border crossings have hit their lowest levels in decades under Donald Trump, with more than 6,000 arrests made in June alone, 15 percent lower than a previous record in March. Trump demanded the border wall be painted black in 2021, during Joe Biden's presidency, warning that "If they don't paint it, bad things are happening.

"The best colour to paint it is black, because if you paint it black, it's so hot, nobody can even try to climb it," Trump explained, and it appears he has finally had his way, though many have questioned both its cost and necessity.

Previous estimates by the Washington Post in 2020, citing government contracting estimates, suggested the cost of the black paint alone could be at least $500million, potentially rising into the low billions depending on the type of paint used.

Many social media users have highlighted another issue that the paint doesn't address - what happens if people attempt to scale the border fence at night?

"Exactly, which is why this is a waste of taxpayer dollars," posted X user Emre Yurttas in response to a video highlighting this glaring oversight.

Many also speculated the majority of illegal border crossings would occur under the cover of darkness, rather than in broad daylight.

However, MAGA enthusiasts have overlooked these concerns, instead hailing Trump as a genius for the decision to paint the wall.

One of the movement's most prominent X accounts, Trump War Room, announced to its 2.5 million-strong following: "GENIUS! Our southern border is being painted black, so it will be too hot to climb in the heat."

Noem has not yet disclosed the cost of the paint job, although approximately $46.5 billion was secured for funding through Trump's One Big Beautiful Bill Act by Homeland Security to overhaul the border system, which includes the construction of an additional 700 miles of primary wall.