Theresa May has told Japan that the UK will stand "shoulder to shoulder" with them over the threat from North Korea.
The Japanese Air Self-Defense Force has conducted Patriot Advanced Capability-3 deployment training at US Marine Corps Air Station Iwakuni, Japan.
Nuclear-armed North Korea has fired a ballistic missile over Japan and into the Pacific Ocean in what is being called a major escalation.
Aircraft from the amphibious assault ship USS America will continue search efforts for 10 missing Sailors assigned to the destroyer USS John S. McCain.
The deployment of 30 British United Nations Command forces personnel has been reported by some newspapers as a major military deployment.
SOUTH CHINA SEA - Guided missile destroyer USS John S. McCain was involved in a collision with the merchant vessel Alnic MC while underway east of Singapore and the Strait of Malacca this morning
Military leaders in the United States and China signed an agreement to improve communication between their militaries and reduce the chances of miscalculations.
North Korea claims it is considering strikes near US military installations in Guam.
More than 3,500 Japanese and US personnel will conduct a bilateral and joint exercise showcasing their capabilities on the Japanese island of Hokkaido in August.
In response to North Korea's ballistic missile launch, two US Air Force B-1B Lancer bombers joined their counterparts from South Korea and Japan for a patrol.