This photo, released by North Korea's official Korean Central News Agency, shows the regime staging major live-fire drills, Oct. 10. Yonhap

The South Korean government on Tuesday called for North Korea to immediately cease tension-escalating activities, a day after Pyongyang said it conducted "tactical nuclear" drills and vowed to strengthen its nuclear force.

On Monday, the North's official Korean Central News Agency (KCNA) said its leader Kim Jong-un inspected an exercise of tactical nuclear operation units to assess the "war deterrent and nuclear counterattack capability" in response to recent joint military trainings by South Korea and the United States.

"The government urges North Korea once again to immediately cease any additional provocations and to respond to our 'audacious initiative' offer," a unification ministry official told reporters, referring to President Yoon Suk-yeol's proposal to help rebuild the North's economy in return for denuclearization steps.