North Korea staged GPS jamming attacks on Friday and Saturday, an operation that was affecting several ships and dozens of civilian aircraft in South Korea, Seoul's military said.
The jamming allegations come about a week after the North test-fired what it said was its most advanced and powerful solid-fuel ICBM missile, its first such launch since being accused of sending soldiers to help Russia fight Ukraine.
The South fired its own ballistic missile into the sea on Friday in a show of force aimed at demonstrating its resolve to respond to "any North Korean provocations".
"North Korea conducted GPS jamming provocations in Haeju and Kaesong yesterday and today," Seoul's joint chiefs of staff said in a statement Saturday, adding several vessels and dozens of civilian aircraft were experiencing "some operational disruptions".
According to Agence France Presse, the military warned ships and aircraft operating in the Yellow Sea to beware of such attacks.
"We strongly urge North Korea to immediately cease its GPS provocations and warn that it will be held responsible for any subsequent issues arising from this," they said in the statement.
Relations between the two Koreas are at one of their lowest points in years, with the North launching a flurry of ballistic missiles in violation of UN sanctions.
It also has been bombarding the South with trash-carrying balloons since May, in what it says is retaliation for anti-Pyongyang propaganda missives sent North by activists.
The South Korean military said Pyongyang also attempted to jam GPS signals in May, but added at the time that it did not hinder any military operations in the South.
In Friday's drill, South Korea fired a Hyunmoo surface-to-surface short-range missile into the West Sea, which the military said was to show Seoul's "strong resolve to firmly respond" to any North Korean threats.
The Hyunmoo missiles are key to the country's so-called 'Kill Chain' preemptive strike system, which allows Seoul to launch an attack if there are signs of an imminent North Korean attack.
