South Korea's military has discovered signs in North Korea of possible preparations to launch a second military satellite into space, informs the Reuters agency.
The activities were spotted in a northwestern region of the country where North Korea's main space flight center is based.
South Korea and US intelligence agencies closely monitor North Korea's activities.
North Korea launched its first spy satellite last year. The launch was met with sanctions by the US and its allies and prompted Seoul to suspend part of a military agreement it signed with Pyongyang in 2018.
In response, Pyongyang canceled the pact and rebuilt previously destroyed guard houses near the border with South Korea. The North Korean state has also promised to launch three more satellites this year.
Pyongyang defended its satellite launch as part of its right to self-defense and condemned Washington's response as a "double standard" relative to the launch of a satellite by South Korea.