North Korea's continued intransigence over its nuclear weapons program remains a threat to the region and the world, Tillerson said.
He was, however, unrelentingly critical of North Korea, a politically and economically isolated nation whose leaders have long viewed the United States as a military threat, in part because of periodic us military exercises with South Korea, which the North sees as preparations for attacks aimed at destroying its ruling elite. "The government will take action in accordance with their free will after the probes", said Lee Duk-haeng, a ministry spokesman.
The U.N. Security Council on Friday unanimously adopted a USA -drafted resolution imposing new targeted sanctions on a handful of North Korean officials and entities, in response to a series of ballistic missile tests this year that are banned under U.N. resolutions.
"But we can not allow China to use its economic power to buy its way out of other problems, whether it's militarizing islands in the South China Sea or failure to put appropriate pressure on North Korea".
Mattis also said that while Washington welcomes China's economic development, economic and political friction between the two sides is anticipated, as the United States can not accept Chinese actions that impinge on the interests of the global community.
"China has indisputable sovereignty over the (Spratly) Islands and their adjacent waters", Hua said, referring to reefs and islets in the South China Sea where Beijing has built installations that could be used by its military.
The drill in the town of Abu, about 800 kilometres (500 miles) west of Tokyo facing the Sea of Japan, simulated a ballistic missile attack in the surrounding mountains in Yamaguchi prefecture which hosts a major US Marine Corps air station, a disaster agency official said.
"Bear with us", Mattis said.
Mattis also discussed a resurgent terrorist threat in the Philippines and said the U.S.is helping to train, advise, assist, and help modernize the nation's forces.
Mattis told the Shangri-La regional defence summit in Singapore at the weekend: "The scope and effect of China's construction activities in the South China Sea differ from those of other countries in several key ways".
"Participants expressed appreciation for U.S. -ASEAN cooperation, noting the 40th anniversary of U.S. -ASEAN relations", Ross said.
But he also said all countries need to "contribute sufficiently to their own security", a key belief held by President Trump.
Visiting Australia with Defense Secretary James Mattis on Sunday, the U.S. top diplomat Tillerson sought to reassure Canberra of the long-standing alliance with Washington.
"We recognize no nation is an island isolated from the others, we stand with our allies and the worldwide community to address pressing security challenges, and do so together", he said.