US President Joe Biden's administration is to build a section of border wall in southern Texas in an effort to stop rising levels of immigration.
About 20 miles (32km) will be built in Starr County along its border with Mexico, where officials report high numbers of crossings.
Building a border wall was a signature policy of Donald Trump as president and fiercely opposed by Democrats.
In 2020, Mr Biden promised he would not build another foot of wall if elected.
His administration passed a proclamation soon after taking office that said building a wall across the southern border "is not a serious policy solution".
On Thursday, however, Mr Biden said he "can't stop" the construction of the border wall because the funding for it had already been appropriated.
When asked whether he believes the wall could work, he replied simply: "no".