North Korea was previously on the list, but taken off in 2008 by the Bush administration during an attempted denuclearization deal. With Iran, Sudan, and Syria also being on the list administered by the State Department, exactly what does being a state sponsor of terror mean?
The step at least symbolically ratchets up the roiling standoff between the US and North Korea over Pyongyang's program to develop nuclear weapons and intercontinental ballistic missiles that could hit the USA mainland.
Some members of Congress had been pushing for years for North Korea to be put back on the list, but others questioned whether the reclusive regime met the criteria of actively sponsoring global terrorism.
Trump said that the formal declaration will be issued Tuesday, along with increased sanctions on North Korea that will be "the highest level of sanctions" ever.
Relations between the US and North Korea have been fraught ever since President Trump took office.
The official added that the country "clearly fit the criteria for a state sponsor of terror in a previous administration".
Some experts, as well as USA officials speaking privately, believe North Korea does not meet the criteria for the designation, which requires evidence that a state has "repeatedly provided support for acts of global terrorism".
Specifically, Klingner cites recent cyberattacks against USA and South Korean targets, including the 2014 attack against Sony Pictures for producing a film critical of North Korean leader Kim Jong Un.
"The regime has made numerous lethal incursions in South Korea, attempted to assassinate senior leaders, attacked South Korean ships and tortured Otto Warmbier, ultimately leading to that fine young man's death", Trump said.
At the request of Warmbier's family, six Democratic and six Republican senators later urged the State Department to consider reinstating North Korea to the list.
Former President Barack Obama removed Cuba from the list in 2015 and Bush, in addition to North Korea, removed Libya in 2006 and Iraq in 2004.
There is also a question about whether such a designation, especially at a time of heightened tension, could further complicate efforts to convince North Korea to give up its nuclear and weapons program.
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