The environmental impacts of preparations for war include: indirect impacts made through the diversion of resources from environmental development and through the impact of the armaments industry; and direct impact through weapons testing and military operations and through the proliferation of nuclear technology. Military bases, especially airfields, may require large areas of ecologically valuable land and require the destruction of any fauna perceived as hindering such activity (such as birds congregating on runways). The construction of such bases tends to destroy such environments irretrievably, especially in the case of island bases which are turned into concrete wastelands. Large sectors of most countries are reserved for military exercises, especially tank manoeuvres, tactical missile exercises, bombing exercises and artillery practice, in addition to those reserved in some countries for chemical and biological warfare exercises. In those countries manufacturing weapons, such areas may also be used for testing missiles, chemical and biological warfare products, as well as nuclear weapons testing. All of these activities severely degrade the natural environment and tend to be treated as exceptions to any regulatory measures to protect the environment.
When Soviet troops withdrew from former East Germany in 1992, it was reported that the larger part of the 1.5 million tonnes of ammunition was being destroyed by "medieval means" – the explosive material was burned, without filters, in the open. Nitrogen oxides, high toxic chemical dioxides, and heavy metals (e.g. mercury) were released to the atmosphere. Under treaty, the munitions should have been removed to Russia, but much of it was found buried on site to avoid the expense of removal. Abandoned garrison towns around Berlin have derelict barracks and villas, wreckage of army vehicles, hidden waste tips with not only ammunition but million of gallons of spent tank and lorry oil, and chemical wastes. Officials have estimated that the 4% of East German territory that was occupied by former Soviet bases and facilities is severely polluted. In Brandenburg, north of Berlin, where a third of the forces were concentrated, the environmental damage damage exceeds Dm 10 billion. Germany had already paid Dm 13 billion to the Russian forces to help finance the withdrawal.
To maintain military flexibility, the US insisted in 1997 that direct military carbon emissions be excluded from international carbon accounting. Those emissions, around 5 percent of the total global, are far less than the indirect emissions from conflict.