Japan has warned of the acute threat posed by North Korea's weapons programs, with the Japanese defense ministry saying in its annual 563-page review that "the security threats have entered a new stage," Reuters reported Aug. 8.

The Defense White Paper said it is possible that North Korea has acquired nuclear warheads and achieved the miniaturization of nuclear weapons. It noted that missiles launched on a lofted trajectory were difficult to intercept.

A group of ruling party lawmakers led by Itsunori Onodera, who became defense minister on Aug. 3, urged Prime Minister Shinzo Abe in March to consider acquiring missiles to hit enemy bases. The move, if realized, would be a drastic change in Japan's defense policy which, thus far, has avoided acquiring weapons to hit other countries.

The defense ministry also noted that Japan's jet scrambles against Chinese aircraft hit a record high in the year to March 2017, warning it was possible that China will further increase its naval and air force activities in the Sea of Japan.

The paper was released after North Korea fired two intercontinental ballistic missiles in July that landed off Japan's west coast.

Meanwhile, U.S. intelligence officials believe that North Korea has successfully produced a nuclear warhead that can fit inside missiles, achieving a critical milestone for it to become a full-fledged nuclear power, The Washington Post reported, citing a Defense Intelligence Agency report dated July 28.