She called on China to take steps to prevent a very unsafe situation emerging and urge the North Korean regime to stand down.
The former secretary of State said that the Chinese are hesitant to exercise their leverage over fears that the North Korean regime could collapse, creating a refugee crisis on their border.
Japan's defense ministry submitted a record budget request of $160 million for missile defense, various military aircraft, new naval vessels, and the development of long-range and hypersonic missiles to break through enemy defenses.
Mr Trump has also given "conceptual" approval to the purchase by the South of billions of dollars of United States military hardware.
Early on Tuesday, the reclusive state fired an intermediate-range Hwasong-12 over Japan, prompting US President Donald Trump to insist that "all options" were on the table in an implied threat of pre-emptive military action.
North Korea said the test fire of a missile that flew over Japan was a "curtain-raiser" for its "resolute countermeasures" against ongoing US-South Korean military drills.
Responding to North Korea's recent intermediate-range ballistic missile launch, US and allied forces flew a joint mission in Northeast Asia on 30th August. It says its weapons programs are needed to counter US aggression. The South wants the maximum warhead weight doubled to one tonne, and the Pentagon has said it was "actively" considering the revision.
A USA ban on travel by Americans to North Korea comes into effect on Friday, a step announced after the death of a U.S. student shortly after his release from a 15-year prison sentence in the country, where three other Americans are still detained.
South Korean analysts said North Korea's threat against Guam and the launch over Japan on Tuesday are likely attempts to make launches over Japan an accepted norm and win itself greater military space in a region dominated by enemies.
Early on during his presidential campaign Trump said he was all right withdrawing the nuclear and security umbrella that the United States provides for South Korea and Japan without which both countries could go nuclear within a month if their security is threatened.