Mullin spoke on CBS News' Face the Nation and tied the decision to President Donald Trump's hardline approach to crime. He credited the Republican leader with "restoring America values".
Critics warn that images of the execution could serve as a propaganda tool for violent groups. Mullin brushed that aside. "I don't see an elevated risk at this point at all because of this," he said. "If you attack America, we will come after you, and we will make sure that the punishment fits the crime."
Hasan, a former US Army major, was sentenced to death in August 2013 after being convicted of killing 12 unarmed active-duty soldiers and a retired serviceman at the Fort Hood military base in Texas. The attack came on November 5, 2009, in a medical facility where service members get routine check-ups before deployment. Another 32 people were injured. Police responding on the base shot Hasan, leaving him paralysed from the waist down.
Others have questioned the optics of broadcasting a firing squad killing of a man in a wheelchair. US lawmakers have called the plan "barbaric," and the pope has called the death penalty "inadmissible."
Hasan's attack ranks among the deadliest mass shootings on a US military base.