British and American marines are set to battle it out in the Mojave Desert, California, on Exercise Green Dagger.
Teaming up with their Dutch counterparts – the Netherlands Marine Corps will be joining them on a new task group deployment next year – UK commandos are testing skills across a range of environments, including a training area the size of Luxembourg.
Training with the US Marine Corps (USMC) will culminate in 'free play battle' to evaluate a combined force with the Netherlands.
Next year, 40 Commando will be at the centre of the high-readiness LRG(S) or Littoral Response Group (South).
The force will focus on the regions east of the Suez Canal, ready to respond to global events – comprising about 500 British and 120 Dutch troops, plus amphibious aircraft and vessels.
Exercise Green Dagger is designed to prepare those involved, with most exercises taking place at the vast Marine Corps Air Ground Combat Centre at Twentynine Palms.
Watch: Future Commando Force – Royal Marines trial new concepts.
About 400 miles north of the primary drills, a team from 40 Commando will arrive at the Mountain Training Warfare Centre in Bridgeport to battle with the Dutch against the USMC.
Marine Sean McGrath from 40 Commando said the interoperability training has been "really rewarding".
"It's been fantastic to work in one of the best training environments in the world. Twentynine Palms is absolutely huge and offers pretty much every type of training possible," he said.
"We can train across terrains, in cities and with so much capable kit. I can see why we come here."
Specialists from across Commando Logistic Regiment, 30 Commando Information Exploitation Group, 24 Commando Royal Engineers and 29 Commando Royal Artillery have joined 40 Commando and the Netherlands Marine Corps in California.
Alongside competitive exercises, the logistics behind the new Future Commando Force have been put to the test.
The desire to deploy smaller groups of marines across broader landscapes to cover more ground has led to the formation of Combat Service Support Troops.
These personnel work independently, outside of the direct chain of command, to keep smaller groups stocked with ammunition and food – the unforgiving desert conditions are a great setting to prove the concept.
Watch: Exercise Green Dragon: How to fuel the Royal Marines' Future Commando Force.