Trump spoke on Saturday night with South Korea's President Moon Jae-in, pledging joint "steps to strengthen deterrence and defence capabilities and to maximise economic and diplomatic pressure on North Korea", according to the White House.
The statement came after Pyongyang's testing of intercontinental ballistic missiles on July 2 and 28 and previous ballistic missile launches and two nuclear tests past year.
In the roughly 50-minute meeting - their first in about two years - on the sidelines of the U.N. General Assembly, the leaders agreed that North Korea's nuclear and ballistic missile development poses a threat to the entire world, Japanese Deputy Chief Cabinet Secretary Yasutoshi Nishimura said.
"That's enemy fire trying to attack R.O.K. forces located there", says Kimmel - referring to South Korea by its official name, the Republic of Korea. United States and South Korean officials have said the North imports some 4.5 million barrels of refined petroleum products and two million barrels of crude oil each year.
Still, despite heated rhetoric and posturing in the United States and North Korea, there has been no positioning of USA military assets to suggest a military conflict is imminent.
Military options available to the United States range from non-lethal actions such as a naval blockade to enforce sanctions to waging cyber attacks and positioning new U.S. weaponry in South Korea, where the United States has 28,500 troops.More news: Ibrahim Halawa acquitted in Egypt - safe return 'imperative'
The KCNA said Kim expressed great satisfaction over the launch, which he said verified the "combat efficiency and reliability" of the missile and the success of efforts to increase its power.
The combined practice came three days after the North fired another intermediate-range ballistic missile over Japan in the wake of a sixth nuclear test early this month.
"So they aim for the middle of the Pacific Ocean, as you know, where at least we hope no ships are around, right?"
In remarks to reporters at the Pentagon, Mattis said US and Japanese missile defenses have been ready to respond, but were not needed.
US soldiers participate in a South Korea-US combined arms collective training exercise at the US army's Rodriguez shooting range in Pocheon, about 70 km northeast of Seoul near the heavily-fortified border with North Korea on September 19, 2017.North Korea bitterly denounced new sanctions on its economy as "vicious, unethical and inhumane" and warned the measures would only accelerate progress on its nuclear weapons programme, state media reported.
"America and our allies will never be intimidated", Trump said in a wide-ranging speech Friday marking the 70th anniversary of the Air Force at Joint Base Andrews, Md."We will defend our people, our nations and our civilization from all who dare to threaten our way of life".