The news comes after crew from two other Asian airlines-Cathay Pacific and Korean Air-reported seeing what they believed was a ballistic missile while they were in the sky on November 29.
An official at the Ministry of Land, Infrastructure and Transport said, "It appears that Singapore Airlines is flying over Busan and the east coast of Japan rather than flying through Gangwon Province and the East Sea".
Shortly after the test, a spokesperson for the U.S. Defense Department acknowledged that the North Korean missile "flew through busy airspace used by commercial airliners".
The missile soared 2,800 miles into space without any apparent issue, but it is unclear how the weapon performed during atmospheric re-entry, as views within the intelligence community appear to vary.More news: Chinese state-run daily publishes nuclear war safety tips
He added: "The most likely reason is simple that they did it for aesthetics".
"We have been in contact with relevant authorities and industry bodies as well as with other carriers".
"At the moment, no one is changing any routes or operating parameters", the Hong Kong-based airline said in a statement. "We remain alert and review the situation as it evolves". The airline said that its flight was "far from the event location" and unaffected by the missile - but that the crew reported the sighting to air traffic control in Japan in line with procedures.
The North has conducted a flurry of missile tests this year in defiance of repeated worldwide protests, including from aviation authorities.More news: 'The Nutcracker' opens with new scenery in second act
The International Civil Aviation Organisation (ICAO) in October condemned the rogue state for its repeated launches, saying they severely undermined the safety of international civilian flying.
South Korea says Pyongyang regularly fails to issue notices to airmen when conducting missile launches.
The chances of a plane being struck randomly by a missile are "billions to one", according to CNN aviation safety analyst David Soucie.More news: Melania Trump, Karen Pence to visit hurricane-battered South Texas
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