The world of the US military, especially the navy and air force, have often proven they do not share President Trump’s scepticism on global warming. And now they have decided to invest part of the 54 billion that Trump has promised to add to the defence budget in favour of green sources. The first projects have already been started up: the Navy is developing a turbine to be installed on sea- and river beds, to produce energy from the currents. The project is meant for the bases where the supply of fuel for generators is particularly difficult and expensive, such as in remote areas of Alaska. The Air Force is in turn installing solar power plants to supply its bases in California and New Jersey. The very same defence secretary appointed by Trump, James Mattis, in a report presented to the Senate, wrote that ''climate change is impacting the stability of the world where our troops are operating today. It is appropriate operative command structures include instability factors that relate to the safety of the environment in their areas in their planning''. But already in September last year, shortly before Trump was elected, twenty five security experts, Republicans and Democrats, published an open letter in which climate change was defined as a '''significant risk'' to national security, demanding an appropriate policy to address it. The group included the Undersecretary of Defence of the George W. Bush administration, Dov Zakheim, and former Marines General Anthony Zinni, also former special envoy to the Middle East. These investments are being pushed by the fact that renewable sources and gas have become increasingly competitive with fossil fuels. Even in everyday life the evidence is there to be seen. As demonstrated by a study, New Energy Finance, made by the company Bloomberg. in 2016 the energy expenditure of US households reached its lowest level in 60 years. Bloomberg states: ''The installation of renewables has forged ahead, consumption and export of natural gas have reached record levels and the economy has grown with more energy-efficiency than ever before''. According to research, in some states renewables are now the cheapest source of energy. In the United States last year they accounted for 22% of energy production. In 2016 gas became the main source of energy, standing at 34%.