The United States has blocked efforts by International Civil Aviation Organization to improve civil aviation in North Korea.

The organization is working with Pyongyang to open a new air route that would pass through North and South Korean airspace.

The U.S. move is part of a negotiating tactic to maintain sanctions pressure on North Korea ahead of a second summit between President Donald Trump and leader Kim Jong Un in Vietnam in late February.

Airlines currently take indirect routings to avoid North Korea due to the threat of unannounced missile launches.