A South Korean official says jamming signals from North Korea have affected 250 civilian flights in and out of South Korea.
Seoul's Transport Ministry said Tuesday the signals have interfered with GPS on flights since Saturday. The planes have relied on alternate navigation systems to prevent trouble.
Lee Kyung-woo of Seoul's Korea Communications Commission says the signals appear to have come from the North Korean border town of Kaesong.
South Korean officials accused North Korea of similar jamming in 2010 and 2011. South Korea's Defense Ministry says its military hasn't been affected.
The two Koreas are technically at war since the 1950's Korean War ended in a truce, not a peace treaty.