The frequency of a major military exercise off Scotland's northern coast will be reduced from three times a year to twice from next year.
Neptune Warrior, which involves Nato and invited countries, has drawn criticism from the Scottish Greens.
Eleanor Scott, Green MSP for the Highlands and Islands, is angry about training at Cape Wrath, Sutherland, which is part of a Unesco Geopark.
The latest round of the exercise will run from 19-30 June.
Neptune Warrior will involve 40 surface ships and submarines and 50 aircraft from the UK, Nato and invited countries.
The MoD said the exercise will focus on training for peacekeeping duties.
There will be low flying and bombardment of the range at Cape Wrath by warships.
The Royal Navy confirmed the number of exercises will be reduced.
This followed a review which determined two exercises made it easier to attract participants and fitted better with RAF training programmes.
Cape Wrath - a long established military firing range - is in a United Nations Educational, Scientific and Cultural Organization (Unesco) European Geopark because the area is considered to be of international geological importance.
Dr Scott said Neptune Warrior was in contravention of government environmental policies, a "disgrace" and should be banned.
She said: "For the government to allow this exercise to take place in this area makes a mockery of the Geopark designation and all the other environmental designations in the area."
The Ministry of Defence said the armed forces take their responsibilities towards the environment "very seriously".
A MoD spokeswoman said: "I think it's unfair but easy to accuse the armed forces of harming the environment.
"We do a huge amount of research and impact studies to make sure we do not harm the environment."