A senior South Korean government official says the country plans to restore guard posts along the border with North Korea, matching a move by the North.

Principal Deputy National Security Advisor Kim Tae-hyo told public broadcaster KBS on Monday that the step is defensive.

Kim said South Korea cannot silently watch an armed opponent provoking Seoul at short distance.

His comments come after the South Korean military released images of North Korea reinstating guard posts and heavy firearms in the Demilitarized Zone.

The posts had been removed under a 2018 agreement reached by South Korea's former administration to ease inter-Korean tensions.

Last week, following North Korea's launch of a military spy satellite, South Korea suspended part of the agreement that imposed no-fly zones.

After Seoul resumed aerial surveillance and reconnaissance activities along the demarcation line, North Korea announced that it would resume all military measures that were halted under the agreement.