A government official said the inter-Korean cooperation to restore air traffic communication had started some time before Wednesday’s flight, with exchanges of brief signals every morning at 7 a.m. Although the official did not elaborate on the exact time, both sides also started exchanging information on weather conditions and observations.

The control tower at Incheon Airport previously handled such tasks with the North until its backup in Daegu started operations last year.

Experts are skeptical that the route will become “permanent” amid the US-led pressure campaign against North Korea. Washington has agreed to support inter-Korean cooperation for the Winter Games, but it is uncertain whether the stance will continue after the Olympics.

“The latest flight to North Korea was greenlighted by the US because it was transporting athletes and Masikryong Ski Resort was nearby Kalma Airport,” Cha Du-hyeogn, a visiting research fellow at the Asan Institute for Policy Studies told The Korea Herald.

“It would be very dangerous to regularize inter-Korean air routes because it goes against the basic spirit of the existing sanctions against the North,” he added.

Wednesday’s flight also drew concerns here, as the US greenlighted the trip at the last minute, before the flight took off. There were concerns from the US and Asiana Airlines regarding a possible sanctions violation, but the issues were resolved, Seoul’s Unification Ministry spokesperson Baik Tae-hyun said at a press briefing.

US unilateral sanctions announced in 2017 against North Korea state that no vessels or aircraft can visit the US within 180 days of going to North Korea. But Washington made special exemptions for the flight.

Aside from the risk of sanctions violations, using the air route also entails military complications and risks as well. The Asiana Airlines aircraft avoided flying directly over the military demarcation line, a de facto border separating the two Koreas, but through a separate route over the East Sea.

The South’s Ministry of Land, Infrastructure and Transport said Thursday that the East Sea air route was drawn for temporary use.

There is also an agreed “no-fly” zone near the MDL that extends to a maritime region in the East Sea. Both Koreas are extremely sensitive about aircraft and drones entering the zone.

The divided Koreas technically remain at war since the end of the 1950-1953 Korean War.

Seoul has also hinted it used the air route instead of a land route out of convenience. Masikryong Ski Resort is only a 45-minute drive from Kalma Airport, a military airfield used for this week’s round-trip.

Cross-border land routes in both eastern and western parts of the South are expected to be more frequently used. Last week, North Korea sent its 12 ice hockey players via the western land route and previously an advance team through the eastern route.

South Korea is hoping that the PyeongChang Olympics could pave the way for improved inter-Korean relations and bring North Korea to denuclearization dialogue.

By Jung Min-kyung (mkjung@heraldcorp.com)