North Korea violated an armistice agreement with South Korea this month when North Korean soldiers shot and wounded a North Korean soldier as he defected across their border and it must not do so again, South Korea's defense chief said Monday.

The defector, a North Korean soldier identified only by his surname, Oh, was critically wounded but has been recovering in hospital in South Korea.

The incident comes at a time of heightened tension between North Korea and the international community over its nuclear weapons program, but the North has not publicly responded to the defection at the sensitive border.