The United States left out North Korea from its latest list of states sponsoring terrorism Thursday, despite persistent calls for putting Pyongyang back on the list.

The State Department's Country Reports on Terrorism 2015 said the North "is not known to have sponsored any terrorist acts since the bombing of a Korean Airlines flight in 1987."

The North was put on the list in 1988 for the airliner bombing that killed all 115 people aboard, but the designation was rescinded in 2008 in exchange for progress in denuclearization talks.

Calls have been persistent for redesignating Pyongyang as a terrorism sponsor since the North was found responsible for the cyber-attack on Sony Pictures.

Earlier this month, U.S. House lawmakers introduced a bill requiring the government to re-examine whether the North should be put back on the list, arguing that they believe the communist nation merits redesignation.

The bill (H.R.5208), submitted last week with Rep. Brad Sherman

(D-CA) joining as a co-sponsor, listed about 20 cases involving North Korea, including its 1987 bombing of a South Korean jetliner and the 2014 cyberattack on Sony Pictures.

The State Department has said redesignation would only be symbolic without big practical effects.

The terrorism report listed Iran, Syria and Sudan as state sponsors of terrorism, removing Cuba from the list in the wake of the restoration of full diplomatic relations between the two countries. (Yonhap)