The Department of Justice is to seek the death penalty for a second time for the Boston marathon bomber after a court overturned the convict's death sentence last month.
Attorney General William Barr said his department would do "whatever's necessary" to ensure Dzhokhar Tsarnaev is put to death.
A federal appeals court in Massachusetts overturned Tsarnaev's sentence last month after a panel found there was reason to believe that the presiding judge at trial did not sufficiently vet the jurors.
In an interview with the Associated Press on Thursday, Attorney General William Barr told the AP: "We will do whatever's necessary.
"We will take it up to the Supreme Court and we will continue to pursue the death penalty."
US Attorney Andrew Lelling later on Thursday, backing the appeal.
"The severity of Tsarnaev's crimes place him in that narrow category of criminals for whom death is a proportional punishment," Lelling said.
"Some have argued that executing Tsarnaev will not deter others from pursuing similar crimes. But, ultimately, this decision is not about deterrence. It is about justice.
He added: "Dzhokhar Tsarnaev is an ideologically driven mass killer."
Trump demanded the death sentence for the bomber, who, alongside his brother Tamerlan, killed three people and injured more than 260 when they detonated a pair of shrapnel-filled bombs along the marathon’s route.
Tamerlan later died following a shootout with cops when he went on the run in the city.
Tsarnaev was sentenced to death in 2015 for his role in the horrific attack but appealed his sentence last year with his lawyers saying it was ridiculous to think there could be impartial jurors in Boston, where his trial was held.
Speaking on the news that the court of appeals had overruled Tsarnaev's initial death sentence, Trump said the federal government must challenge the decision for the sake of those who died in the murderous atrocity on April 15, 2013.
He tweeted: "Rarely has anybody deserved the death penalty more than the Boston Bomber, Dzhokhar Tsarnaev.
"The court agreed that this ‘was one of the worst domestic terrorist attacks since the 9/11 atrocities.’ Yet the appellate court tossed out the death sentence. So many lives lost and ruined.
"The Federal Government must again seek the Death Penalty in a do-over of that chapter of the original trial.
"Our Country cannot let the appellate decision stand. Also, it is ridiculous that this process is taking so long!"
Tsarnaev, 27, and his older brother Tamerlan killed three people and injured more than 260 when they detonated a pair of shrapnel-filled bombs along the marathon’s route.
Tamerlan later died following a shootout with cops when he went on the run in the city.
Tsarnaev was sentenced to death in 2015 for his role in the horrific attack but appealed his sentence last year saying it was ridiculous to think there could be impartial jurors in Boston, where his trial was held.
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Rick DesLauriers, who led the FBI’s Boston office during the bombings, said he hopes they petition the Supreme Court to review the federal appeals court decision and possibly eliminate the need for another trial.
He said the ruling as an “unfortunate example of judicial activism” and “a slap in the face” to the jurors.
“It’s an unnecessarily painful resurrection of this issue for the victims and their families,” said DesLauriers, who retired from the FBI about three months after Tsarnaev’s capture