It added that Trump provided his "conceptual approval" of South Korea's purchase of American military equipment worth billions of dollars, without adding further details.
Harris encouraged greater trilateral cooperation among the United States, Japan and South Korea, which he called a partnership with a objective to meet the North Korean threat, the captain added.
Technically, both the countries remain at war since a truce was declared to end the 1950-1953 Korean War but was never followed by a peace agreement.
North Korea fired a Hwasong-12 missile on August 29 capable of carrying a nuclear payload that traveled almost 2,700 kilometers into the Pacific and triggered alert warnings as it flew over Japan's northern island of Hokkaido.More news: UK's PM Theresa May reassures on Brexit, backs Japan on North Korea
North Korea has been working to develop a nuclear-tipped missile capable of hitting the United States and has recently threatened to land missiles near the US Pacific territory of Guam.
The 1979 guideline was last amended five years ago to extend the allowed range of South Korean ballistic missiles to nearly 500 miles and increase their payload to 1,100 pounds. In turn, South Korea would be free to increase its own tariffs on US goods.
The two countries agreed to the cap as part of a commitment to a voluntary global arms-control pact known as the Missile Technology Control Regime, aimed at limiting the proliferation missiles and nuclear weapons.
The White House said on Friday, the two leaders "pledged to continue to apply strong diplomatic and economic pressure on North Korea and to make all necessary preparations to deter and defend against the growing threat posed by North Korea".More news: Zambia cut Super Eagles' lead in Group B with win over Algeria
The free trade question comes at a sensitive time diplomatically, with the United States and South Korea working in tandem to counter aggression from North Korea through its development and testing of nuclear weapons and long-range missiles.
It came as the US and South Korean forces were nearing the end of the 10-day annual Ulchi Freedom Guardian joint exercises, which the North regards as a rehearsal for invasion.
North Korea defends its weapons programs as necessary to counter perceived USA aggression, such as recent air maneuvers with South Korean and Japanese jets.More news: Are Analysts Bullish Workspace Group plc (LON:WKP) After Last Week?
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