The US-Mexico border in Nogales (Picture: PA).
The US Supreme Court has allowed the Trump administration to use billions of dollars of Pentagon funds to build sections of a border wall with Mexico.
The court ruled by five votes to four to give the administration the green light to begin work on four contracts it has awarded using Defence Department money.
Funding for the projects had been frozen by lower courts while a lawsuit over the money proceeded.
The justices' decision to lift the freeze on the money allows President Donald Trump to make progress on a major 2016 campaign promise heading into his race for a second term.
He tweeted after the announcement: "Wow! Big VICTORY on the Wall.
"The United States Supreme Court overturns lower court injunction, allows Southern Border Wall to proceed.
"Big WIN for Border Security and the Rule of Law!"
The court ruling means parts of the wall can start being built in Arizona, California and New Mexico.
The case the Supreme Court ruled in began after the 35-day partial government shutdown that started in December 2018.
President Trump ended the shutdown in February after Congress gave him approximately $1.4bn (£1.1bn) in border wall funding.
But the amount was less than the 5.7 billion dollars (£4.6bn) he was seeking.
President Trump then declared a national emergency to take cash from other government accounts to use to construct sections of the wall.
The money he identified includes $3.6bn dollars (£2.9bn) from military construction funds, $2.5bn dollars in Defence Department money and $600m (£484m) from the Treasury Department's asset forfeiture fund.
The case before the Supreme Court involved just the $2.5bn in Defence Department funds, which the administration says will be used to construct more than 100 miles of fencing.
The other funds were not at issue in the case.
The transfer of the $3.6bn in military construction funds is awaiting approval from the US Defense Secretary.