Four more of Japan's 34 PAC-3 units, largely used to defend the capital region, were relocated to southwestern Japan recently after North Korea warned of sending missiles toward the USA territory of Guam.
Chinese President Xi Jinping and U.S. President Donald Trump spoke by telephone about keeping pressure on North Korea using economic sanctions imposed through the United Nations, the White House has said.
He said he wanted North Korea, which never reached a formal peace treaty with the South after the 1950-53 Korean War - to attend next year's Winter Olympics to be hosted by South Korea.
He did not provide details, but he responded affirmatively when asked if these included options that would not put Seoul at grave risk.
Tensions flared when Kim Jong-Un's regime tested what it termed a hydrogen bomb many times more powerful than its previous device.
"The bottom line is that in the missiles, were they to be a threat, whether it be the United States territory Guam, obviously Japan, Japan's territory, that would elicit a different response from us", he said.
The bottom line, he said, is that if the missiles were a threat to Guam or Japan, "that would elicit a different response from us".
Another expert has called into question the value of a Washington Post report last month stating that North Korea may be able to fit a miniaturized warhead on an intercontinental missile.
In addition, Aegis ships from the United States, Japan and South Korea are expected to take part in an exercise scheduled from the end of September through the beginning of October to detect and track ballistic missiles.
Following the September 15 test, US Defense Secretary James Mattis said Monday that the US has not seen a reason to shoot down any North Korean missiles as of yet.
An official directly familiar with options planning within the Trump administration told CNN the question that now needs to be answered is whether North Korea's missile program has progressed to the level of being such an inherent threat that the Pentagon would recommend targeting a missile even if its trajectory did not indicate it would hit the U.S. or its allies. South Korea says the USA military flew powerful bombers and stealth jets over the Korean Peninsula in joint drills with South Korean warplanes.
The US flew four F-35B stealth fighter jets and two B-1B bombers over the Korean peninsula today in a blunt show of force.
Instead, he said, the global community should strictly implement the sanctions imposed on North Korea by the U.N. Security Council.
"Bluster, threat and hyperbole" also seem to be the order of the day when it comes to exchanges between the USA leader and the country it has never technically come to peace with.