The US Secretary of Homeland Security Kirstjen Nielsen, who enforced some of President Donald Trump's controversial border policies, has resigned.
The US Secretary of Homeland Security Kirstjen Nielsen, who enforced some of President Donald Trump's controversial border policies, has resigned.
The US-Mexico border has reached "breaking point", US officials say, amid an "unprecedented" surge in migrant numbers.
The Pentagon has authorised the transfer of $1bn (£758m) to army engineers for new wall construction along the US-Mexico border.