SEOUL – North Korea has not yet acquired the technology of developing an intercontinental ballistic missile that is capable of reaching the U.S. mainland, a South Korean Defense Ministry official said Wednesday.

In a briefing about the 2016 South Korean Defense White Paper, which was also released Wednesday, the official said South Korea has removed the ministry’s previous assessment included in the 2014 white paper that North Korea is believed to possess the capability of threatening the U.S. mainland with its missiles.

“North Korea has not yet completed an ICBM and has not yet reached the stage that can earn credibility,” the official said.

The official added that North Korea is trying to perfect the flight capability of its submarine-launched ballistic missiles.

The biennial report also said North Korea has about 50 kilograms of weapons-grade plutonium, having obtained about 10 kg last year through reprocessing of nuclear materials.

The 2014 defense white paper said North Korea is estimated to have about 40 kg of such plutonium.

A North Korean Foreign Ministry spokesman said Sunday that Pyongyang could carry out an ICBM test at any time and location determined by its leadership.

In response, the United States said it would shoot down any missiles that threaten its territory or that of its allies.

Ahead of U.S. President-elect Donald Trump’s inauguration on Jan. 20, North Korean leader Kim Jong Un said in a New Year address that his country has entered the final stage of preparing to test-launch the long-range missile.

Kim’s regime conducted two nuclear tests and test-launched more than 20 ballistic missiles last year in defiance of U.N. Security Council resolutions.

As for relations with Japan, the latest South Korean defense white paper maintained the position that the South will continue to make a resolute and stern response to Japan’s territorial claim over South Korea-controlled islets of Dokdo in the Sea of Japan. The islets are known as Takeshima in Japan.

Aside from the territorial dispute, South Korea will continue to cooperate with Japan in coping with North Korea’s nuclear and missile threats for the sake of peace and stability on the Korean Peninsula and in Northeast Asia, the paper said.