UK joins US, Japan and France to practise amphibious landings on Guam
Troops from the UK, France, US and Japan are gathering on remote US islands in the Pacific for drills they say will show support for the free passage of vessels in international waters.
The exercises come amid fears China could restrict movement in the South China Sea.
The drills around Guam and Tinian may also send a message to North Korea about the US commitment to the region and the breadth of its allies.
Tensions between the US and North Korea spiked last month after Pyongyang launched a ballistic missile and the US sent an aircraft carrier strike group to the region.
The drills, which are led by France, will practise amphibious landings, delivering forces by helicopter and urban patrols.
Two ships from France are taking part, both of which are in the middle of a four-month deployment to the Indian and Pacific oceans.
Joining are UK helicopters and 70 UK troops deployed with the French amphibious assault ship FS Mistral.
Parts of the exercise will feature British helicopters taking US Marines ashore from a French ship.
"The message we want to send is that we're always ready to train and we're always ready for the next crisis and humanitarian disaster wherever that may be," said US Marine Corps Lt Col Kemper Jones, the commander of the 3rd Battalion, 8th Marine Regiment.
About 100 Marines from his unit will be part of the drills this weekend and next week.
China claims virtually the entire South China Sea and has aggressively tried to fortify its foothold in recent years by transforming seven mostly submerged reefs into island outposts, some with runways and radars and, more recently, weapons systems.
This has prompted criticism from other nations, who also claim the atolls, and from the United States, which insists on freedom of navigation in international waters.
Critics fear China's actions could restrict movement in a key waterway for world trade and rich fishing grounds.
China says its island construction is mainly for civilian purposes, particularly to increase safety for ships.
It has said it will not interfere with freedom of navigation or overflight, although questions remain on whether that includes military ships and aircraft.