The trust said it will cost millions to demolish the station
The closure of a military rocket range radar station on St Kilda will cost the National Trust for Scotland millions of pounds, the charity has warned.
The site on Hirta, the main island in the remote archipelago, along with facilities on South Uist and Benbecula have been earmarked for downgrading.
A petition opposing the plans has been handed in to 10 Downing Street by campaigners.
The trust said it faced huge fees removing the defunct station.
The bill for conserving the dual World Heritage site will also escalate said the trust as it shares power, water, transport costs with the Ministry of Defence and its contractor QinetiQ.
Michael Hunter, the trust's director of properties and visitor services, said: "As a charity, we would struggle to find the extra funds needed to cover the costs of running operations on St Kilda.
"Inevitably, we would look to public bodies to help support us in our vital work to protect and preserve this wonderful place for the benefit of everyone."
A petition raised against plans to cut jobs at the rocket test range and its associated sites on the Western Isles was handed into Prime Minister Gordon Brown's office by members of the Hebrides Range Taskforce.