North Korea slammed Japan's recent decision to acquire the capability to strike enemy bases and vowed Tuesday to "take a resolute and decisive military step" to defend national sovereignty, according to the Korean Central News Agency.

"We will continue to show in practice how much the DPRK is concerned and displeased with Japan's unreasonable and greedy attempt to realize its wild ambition," a North Korean Foreign Ministry spokesman was quoted as saying by KCNA, using the acronym of his country's formal name, the Democratic People's Republic of Korea.

The spokesman claimed what Japan advocates in its new security policy, adopted last week, is "the preemptive attack capability to strike other countries' territory from A to Z" and "a wanton violation" of the U.N. Charter as well as "a serious challenge to the international peace and security."

"With Japan's formulation of its new aggression line, the security environment in East Asia has undergone a radical change," the statement said.

In its latest National Security Strategy adopted on Friday, Japan described moves by North Korea as a "graver and more imminent threat than before," referring to its repeated ballistic missile launches.

Meanwhile, Kim Yo Jong, sister of North Korean leader Kim Jong Un, suggested Tuesday in a statement carried by KCNA that Pyongyang could test-fire an intercontinental ballistic missile on a normal trajectory rather than a lofted one.

In response to South Korean experts who contend the North cannot verify its ICBM atmospheric re-entry technology without conducting a test on a normal trajectory, Kim Yo Jong said, "I can clear up their doubt about it."

"They will immediately recognize it in case we launch an ICBM in the way of real angle firing straight off," said Kim, the vice department director of the Central Committee of the ruling Workers' Party of Korea.

So far, Pyongyang has conducted all its ICBM tests on a lofted trajectory. A new type of "Hwasong-17" ICBM launched on Nov. 18 is believed to have the potential to travel over 15,000 kilometers and reach the U.S. mainland if launched on a normal trajectory.

Kim Yo Jong also countered South Korean evaluation that satellite images taken by the North were of "inferior" quality, asking, "Who will install and test an expensive high-resolution camera for a single-shot test which takes no more than 830 seconds?"

Pyongyang released Monday aerial photo images of the South Korean capital Seoul and the nearby city of Incheon following what it claims to be an "important final-stage test" for the development of a military reconnaissance satellite that it aims to complete by next April.

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