Seoul
The United States has blocked efforts by a UN agency to improve civil aviation in North Korea at a time when Pyongyang is trying to reopen part of its airspace to foreign flights, three sources familiar with the matter .

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

If the space was deemed safe, international airlines could save fuel and time on some routes between Asia and Europe and North America, and North Korea could begin reviving its own commercial aviation industry.

The cash-strapped country has a population of more than 25 million but its economy has been squeezed by a series of sanctions for its nuclear and ballistic missile programmes.

Washington is seeking concrete commitments from Pyongyang at the summit to abandon its nuclear and missile programmes.Airlines currently take indirect routings to avoid North Korea due to the threat of unannounced missile launches, which have been witnessed by some passengers on commercial flights.

Montreal-based ICAO was prepared to help improve North Korea’s aviation system by leading training sessions between its military and civil aviation staff, two sources said.