The Pyongyang regime, at the time under the command of Kim Jong-il, was taken off the list in 2008 under the presidency of George W Bush, who hoped to engage the reclusive nation in dialogue.
But according to the new report, written by North Korea expert Joshua Stanton for the Committee for Human Rights in North Korea (HRNK), America's standards for defining a state sponsor of terror are "vague and inconsistent."
"Since 2008, North Korea has increased its use of terrorism as an instrument of state policy, and also appears to have increased its material support for designated terrorist organizations," HRNK Executive Director Greg Scarlatoiu said in a statement accompanying the report's release.
"North Korea's recent conduct poses a particular threat to human rights activists and dissidents in exile. It has also repeatedly threatened the civilian population of South Korea and other nations, including the United States," he added.
The report details several instances of North Korea's alleged support of terrorism.
In 2009, just one year after it was removed from the blacklist, there were several interceptions of North Korean shipments "to Iran and its terrorist clients (that) evidenced the importance of North Korea's role as a supplier of arms to terrorists backed by Iran," the report states.
"News reports have alleged that these arms were destined for Iran's terrorist clients, including Hezbollah and Hamas," Stanton writes in the report.
Washington accuses Pyongyang of being behind the hack that led to the release of embarrassing company emails and caused Sony executives to halt the debut of the film "The Interview.
