New South Korean Defense Minister Lee Jong-sup took office Wednesday, vowing to "sternly" respond to North Korea's possible provocations and cement the alliance with the United States.

In his inauguration speech, Lee, a retired three-star Army general, stressed his commitment to ensuring a "robust" defense as he pointed to the "very grave" security context marked by the North's evolving nuclear and missile threats and an intensifying Sino-US rivalry.

"If North Korea conducts a tactical provocation, we will sternly respond in light of our right to self-defense," Lee said, referring to the North's possible military steps that "directly" undermine the South's security.

"We will increase cohesion in the military alliance between South Korea and the US and expand mutually beneficial defense cooperation with friendly nations," he added.

His inauguration came as the allies are stepping up security coordination amid forecasts that the North could carry out a nuclear test between new President Yoon Suk-yeol's inauguration on Tuesday and US President Joe Biden's visit to Seoul for their first in-person summit slated for May 21.

In the speech, Lee also pledged to "dramatically" strengthen the country's so-called three-axis system designed to counter the North's security threats.

The system consists of the Korea Massive Punishment and Retaliation (KMPR), an operational plan to incapacitate the North Korean leadership in a major conflict; the Kill Chain preemptive strike platform; and the Korea Air and Missile Defense system (KAMD).

The new minister also expressed his wish to develop the defense industry into a "strategic cutting-edge industrial sector that leads our economic growth."

A graduate of the Korea Military Academy, Lee previously served in various high-profile military positions, such as the vice chairman of the Joint Chiefs of Staff and the commander of the Army's 7th Corps. (Yonhap)