Trump’s choice to lead the Centers for Disease Control disagreed with Trump’s absurd claim that building the wall at the Mexican border will slow the spread of the coronavirus.

Robert Redfield, director of the Centers for Disease Control and Prevention, said Tuesday he was unaware of any indication from his agency that physical barriers along America’s borders would help halt the spread of the coronavirus in the U.S. — contradicting an assertion President Donald Trump made earlier in the day.

Appearing before House lawmakers to testify about the public health crisis and the White House’s budget request for his agency, Redfield was asked by Rep. Katherine Clark (D-Mass.) whether the CDC’s recommendations for combating the coronavirus addressed whether “structural barriers” at the borders “would be of any use in mitigating” the growing outbreak.

“Not that I’ve seen,” Redfield replied.

As the federal government has struggled to mount a cohesive response to the coronavirus threat over the past few weeks, Trump has repeatedly promoted the administration’s move in late January to bar entry from foreign nationals who had recently been in China and institute a mandatory two-week quarantine for U.S. citizens returning from the epicenter of the outbreak.

On Tuesday morning, Trump claimed his campaign trail pledge to build a wall along the U.S.-Mexico border would also aid in containing the coronavirus, tweeting the structure is “Going up fast” and “We need the Wall more than ever!”