President Joe Biden is coming under fire from both sides of the political spectrum after his administration announced new border wall construction in Texas.
Mr Biden has claimed he “can’t stop” construction because funding for it was appropriated in 2019.
The Department of Homeland Security, however, has said there is an “acute” need for the barriers.
Over 2.2 million migrants have been detained this fiscal year alone.
The growing number of migrants in US cities such as New York have increasingly become a challenge for Mr Biden, who has faced intense criticism over his handling of the border.
According to US officials and President Biden, funding for the new border barrier – first announced in late June – was appropriated during the 2019 fiscal year, while Donald Trump was president.
Approximately 20 miles (32km) of new border barriers will be built in Starr County, a sparsely populated stretch of border in the Rio Grande Valley.
In 2020, Mr Biden promised he would not build another foot of wall if elected.
A senior administration official on Thursday laid the blame for the new construction on the US Congress, claiming it resisted efforts to “rescind” the funds in Mr Biden’s first budget request issued in May 2021.
Under a 1974 law, appropriated funds must be made available for their intended purpose unless a rescission is approved by both the Senate and House of Representatives.
“We have repeatedly asked Congress to rescind this money but it has not done so and we are compelled to follow the law,” Homeland Security secretary Alejandro Mayorkas said in a statement.
Mr Biden and the statements stand in stark contrast to a notice about the project on the US Federal Registry.
In that, Mr Mayorkas said there is “presently an acute and immediate need to construct physical barriers and roads in the vicinity of the border of the United States in order to prevent unlawful entries into the United States in the project areas”.
Representative Henry Cuellar, a Democrat whose district encompasses Starr County, told the BBC he does not believe his constituents “will be very happy” with the announcement.
“I am still against a 14th-Century solution – called ‘the wall’ – for a 21st-Century problem,” he said.
“I want to see more personnel, more technology”.
Democratic Congresswoman Alexandria Ocasio-Cortez called it a “cruel policy” and has urged President Biden to “reverse course”.
“The US must take examining the root of migration more seriously,” she said in a statement.
Some Republicans have also criticised Mr Biden for what they see is an abrupt pivot to policies he campaigned against.
Building a border wall was a signature policy of Donald Trump as president and fiercely opposed by Democrats, including Mr Biden.
“He did not think walls work, which is total insanity,” North Carolina Republican Representative Ralph Norman told the BBC.
“What’s changed? I’ll tell you what’s changed – the American people are sick and tired of seeing their cities overrun their hospitals or their schools, and for the police having to deal with illegals.”
The administration is also facing criticism from advocacy groups such as the American Civil Liberties Union, or ACLU, which called the decision “a profound failure”.
“On the campaign trail, President Biden put it best when he said that the border wall is not a serious policy solution – and we couldn’t agree more,” ACLU border strategies director Jonathan Blazer said in a statement.
“Instead of upholding this promise, the Biden administration is doubling down on the failed policies of the past that have proven wasteful and ineffective.”
US Border Patrol apprehended 181,059 people along the southern border in August compared with 132,648 in July, according to the latest data.
In total, more than 2.2 million people have been detained since the beginning of the current fiscal year, which began in October 2022.
On Thursday, the administration also announced that it will resume deportations of illegal Venezuelan migrants, about 50,000 of whom arrived at the US-Mexico border in September alone.