For the first time, Nato is holding a major military exercise in a non-member country, Croatia. The BBC's Nick Hawton has been given access to the Noble Midas 07 exercise.
A Spanish fighter pilot emerges from his cockpit after his warplane touches down on the UK aircraft carrier, HMS Illustrious.
Lt Lopez describes the exercise as "a great experience"
He takes his helmet off and joins several Italian fighter pilots who have already gone below decks. The French air traffic controller who brought them in is on the bridge talking to his British colleagues.
This is a sign of how Nato is changing. With the military forces of Western nations stretched, particularly those of the US and UK, flexibility and adaptability are becoming increasingly important.
"It's a great experience because right now all these countries are working together. You realise you can operate as a joint force community," says Spanish pilot Lt Eduardo Lopez.
In the operations room on HMS Illustrious, Cmdr Tom Cunningham says integrating forces at this level has simply not happened before.
A dozen Nato nations are taking place in the exercise
"I think it indicates both the way we must go and the willingness we have to go that way," he says.
"But it also makes sense in terms of cost. Military equipment is hugely expensive and it's impossible for each nation to hold individually the whole repertoire. What we're seeing here is the ability of several nations to provide a capability together that no-one could alone."
The exercise, being conducted by Nato's Response Force, is based on the scenario of a military conflict in a breakaway province in the Balkans.
It appears to be a thinly disguised reference to current events in nearby Kosovo, whose its majority ethnic Albanian population is seeking independence from Serbia.
But any direct links are denied by French Rear Adm Alain Hinden, who is in charge of the Noble Midas exercise.
"This exercise has been designed for years. The UN and Nato are training for this type of real intervention, of humanitarian assistance be it in this region or anywhere else in the world," he says.
A dozen Nato nations are taking part, including new members Romania and Bulgaria. Would-be members Croatia and Albania are also represented.
But public opinion in Croatia itself is divided over whether the country should join the organisation.
Croats are divided over the Nato membership issue
On the seafront in Split, the city where the exercise is being co-ordinated, people have mixed views.
"My friend's a fisherman and he said there has been nothing to catch for the past week because of all these ships," says 44-year-old Anton Perkovic.
"I am not sure whether the country really needs to be in Nato. What benefits would there be for me?" he says.
But Maria Krekic, a student, says it would be good for Croatia to join Nato.
"We need to join international organisations like this. It will also help provide us with security in the long term," she says.