A vast swathe of Dartmoor could be permanently handed over to the military despite campaigners' concerns that it could ruin the "natural beauty" of the park.
The Ministry of Defence has been using 2,095 acres of moorland at Cramber Tor, on the south west of the moor, for training exercises since 1981 under a succession of agreements with the Dartmoor National Park Authority.
A change in the law, which removes Crown immunity for planning, means the Ministry of Defence (MoD) is now seeking formal planning permission to use the land.
Training activities include battlefield simulation exercises involving the use of pyrotechnics, blank ammunition and low-flying helicopters, as well as adventure, fitness and navigation exercises.
The move has been opposed by the Dartmoor Preservation Association, Ramblers and Open Spaces Society among others. While they accept past training has caused few problems, they fear permanent permission could lead to an escalation in activity, threatening the habitat in the Cramber Tor area, which is home to a number of unique ancient monuments.
James Paxman, chief executive of the association, said: "While we have no objection to adventure training, we are deeply concerned at the possibility of battle simulation, which would destroy the peace of this tranquil area and frighten walkers and riders.
"The national park authority can only be sure of maintaining the current low-impact training if it imposes new conditions to govern troop levels, aircraft movements and the use of pyrotechnics. Otherwise there is a serious risk that it can be escalated out of control in future. It is particularly disturbing that the park authority is proposing an unlimited permission."
Members of the park authority's development management committee meet to discuss the application tomorrow. A report to the committee recommended that "permanent planning permission should now be granted subject" subject to a number of conditions.
It said there was a "wealth of information" which "strongly suggests" that past military activity has "no adverse impact on ecology, biodiversity, archaeology, landscape character, or even recreational enjoyment".
"The use of this land for the purposes described in the application has happened over a long period of time stretching back over 30 years," it states.
"There is no compelling evidence that the use has impacted adversely on biodiversity or archaeology. The use has impacted occasionally it appears on quiet enjoyment and recreation and it can be argued that military training has the potential to be very damaging to this National Park purpose."
There was also "no doubt" of the need for military training and that Cramber Tor was "essential and cannot be accommodated in existing training areas".
An MoD spokesperson said: "The MOD has used the Cramber Training Area since the 1980s through a series of temporary consents the latest of which expired in early January. "The MOD has identified an enduring military need for this training area and has carried out a range of surveys and assessments, to re-assure both itself and the DNPA that the current level of training can be sustained without detriment to the environment or public enjoyment of the area. "The MOD submitted a planning application to DNPA in August 2012 seeking permission to allow military training to continue for an indefinite period. The planning application does not involve the provision of any infrastructure and is purely permission to carry out ‘dry’ training activities, which do not involve live ammunition."