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(This version of the story corrects headline and text to 13 countries as UK did not participate)

NATAL AIR FORCE BASE, Brazil (Reuters) - The air forces of 13 nations including the United States are taking part this week in air combat exercises and non-conventional warfare training at a base in northern Brazil, the Brazilian Air Force said on Wednesday.

Some 100 planes are involved in the so-called Southern Cross or CruzEx exercises, including six F-16 from the Texas Air National Guard alongside aircraft from Brazil, Canada, Chile, France, Peru and Uruguay.

They practiced simulated scenarios to prepare for potential events across the world including peacekeeping and stability operations, as well as providing support in humanitarian response operations in the aftermath of natural disasters.

“The purpose of CruzEx is to increase cooperation and share experiences to be able to act with greater synergy,” said Brazilian Air Force Brigadier Luiz Guilherme Medeiros, director of the air exercises organized in Brazil since 2002.

There was greater emphasis on non-conventional warfare this year, with troops parachuting from planes and rappelling down ropes from helicopters.

Venezuela, which took part with F-16s at the last gathering in 2013, did not bring any aircraft this year.

The Natal Air Force Base, on the northeastern tip of Brazil, played an important role in Brazilian cooperation with the U.S. military during World War II as a refueling station for aircraft flying troops and equipment to Northern Africa.

In 1943, U.S. President Franklin Roosevelt met at the base with Brazilian President Getulio Vargas on his way back from a conference with British leader Winston Churchill in Casablanca.