Campaigning often sees politicians looking to shake hands and deliver speeches in front of sometimes large audiences in settings without security checkpoints.
Representatives from the three countries met Friday for talks in Washington, where they discussed the security environment on the Korean Peninsula and in the region.
At the Karuizawa summit, Foreign Minister Yoshimasa Hayashi is expected to stress that European and Indo-Pacific security are inseparable.
North Korean leader Kim Jong Un said the new ICBM, called a Hwasong-18, would "radically promote the effectiveness of its nuclear counterattack posture."
The rare activation of the country's J-Alert warning system had initially urged residents to take shelter either inside buildings or underground.
The nuclear-armed North has reacted angrily to a recent spate of joint military exercises between the U.S. and South Korea — some of the largest in five years.
The presidential office in Seoul said that a "significant portion" of the information in leaked classified Pentagon documents detailing apparent U.S. spying on Seoul is untrue.
The three days of exercises saw Chinese forces conduct training involving an aircraft carrier and simulated strikes by warplanes carrying live ammunition under "actual combat conditions."
Taiwan’s Defense Ministry said it had detected fighter jets, heavy bombers, reconnaissance planes and other aircraft conducting multiple sorties around the island.
China kicked off three days of military drills and "combat readiness patrols" around the island on Saturday, just days after the Taiwanese president met the U.S. House speaker.
