North Korea has fired a ballistic missile towards the sea off its east coast, South Korea’s military said on Friday.

South Korea’s Joint Chiefs of Staff did not immediately provide details, Yonhap news agency reported.

The development comes at a time that Russian President Vladimir Putin is visiting the Chinese city of Harbin as part of his two-day State visit to China.

Yonhap said the launch comes after the North fired 600-mm super-large shells, considered to be short-range ballistic missiles, toward the East Sea on April 22.

Pyongyang has been conducting a series of cruise missile tests since late January.

Meanwhile, Kim Yo-jong, the influential sister of North Korean leader Kim Jong-un today, said that North Korea’s tactical weapons, including multiple rocket launchers and missiles, are intended to deter South Korea from engaging in “any idle thinking,” in an apparent reference to the South Korea-US joint military drills.

In April this year, North Korea reportedly conducted a tactical drill simulating a nuclear counterattack, featuring super-large multiple rocket launchers.

Leader Kim Jong-un guided the drill to operate super-large multiple rocket units that will have an “important role in substantially strengthening the prompt counterattack capacity of the state nuclear force,” Yonhap had quoted the Korean Central News Agency (KCNA) as saying.

The missile launches coincided with a two-week joint annual air exercise between South Korea and the United States aimed at enhancing readiness against North Korea’s military threats.