US President Donald Trump has authorised the deployment of National Guard troops in Chicago, White House spokeswoman Abigail Jackson confirmed at the weekend, citing what she called “ongoing violent riots and lawlessness” that local leaders have failed to quell.

“President Trump will not turn a blind eye to the lawlessness plaguing American cities,” she said as she announced that 300 troops would be assigned to protect federal officers and assets in the Illinois state capital.

Illinois Governor JB Pritzker, a Democrat, branded Mr Trump’s action “an unnecessary and manufactured performance — not a serious effort to protect public safety.

“This morning, the Trump Administration’s Department of War gave me an ultimatum: call up your troops, or we will,” he said in a statement.

“It is absolutely outrageous and un-American to demand a governor send military troops within our own borders and against our will.”

The president has long threatened to send troops to Chicago, but it was not immediately clear when they would be deployed.

Mr Trump deployed the National Guard in Los Angeles over the summer and in the national capital Washington.

The president also vowed last month to dispatch federal troops to Portland, Oregon, but a judge temporarily blocked the deployment on Saturday.