Video report by ITV News Correspondent Allegra Stratton, in Washington
The US Justice Department scheduled the execution of five death row federal inmates after carrying on a two-decade long dormant policy of the government's use of capital punishment.
The department confirmed five inmates, who had been convicted of murders or rapes of children or the elderly, will be executed in December and early next year.
Barr approved a new procedure for lethal injections that replaces the three-drug cocktail previously used in federal execution with a single drug, pentobarbital.
This is similar to the procedure used in several states, including Georgia, Missouri and Texas.
"Under administrations of both parties, the Department of Justice has sought the death penalty against the worst criminals," Mr Barr said in a statement.
"The Justice Department upholds the rule of law - and we owe it to the victims and their families to carry forward the sentence imposed by our justice system," he added.
The move represents a dramatic reversal after more than a decade-long hiatus in the federal use of capital punishment, as the US President called to "bring back the death penalty".
The death penalty was outlawed at state and federal level by a 1972 Supreme Court decision but reinstated in 1988.
According to data collected by the Death Penalty Information Center, 78 people were sentenced to death between 1988 and 2018 but only three have been since executed.
In 2014, then-president Barack Obama directed the department to conduct a review of capital punishment and issues surrounding lethal injection drugs.
That review resulted in what effectively was a freeze on executions.
The department said the Bureau of Prisons has completed the review and the executions can continue.