The MoD has succeeded in overturning the local authority’s decisions to give the go-ahead for the separate “windfarms” on the Outer Hebrides.
The Government department had raised judicial review proceedings over the outcome of Comhairle nan Eilean Siar (Western Isles Council) committee meetings which approved the developments at Bornish and Frobost on South Uist last year.
They maintained that the turbines have the potential to interfere with air defence radar.
The MoD said a false “aircraft-like return” could be produced and a high concentration of turbines in the area produces a high risk of such returns and increases the risk of false alarms.
They also claimed that the turbines could also produce “clutter” which desensitises the radar system and increase the risk it may fail to detect aircraft.
The ministry had raised objections to applications for new turbines to go up at the sites.
Following a hearing at the Court of Session in Edinburgh before judge Lord Doherty, the decisions of the council committee were set aside.
A spokesman for Western Isles Council said: “We have not seen the exact ruling from Lord Doherty yet and it would not be appropriate to comment in any detail at this stage.
“However, it is likely that the Comhairle will need to reconsider the applications.
“Therefore, it would not be appropriate to make comment on the merits of the three proposals at this time.”
The Hebrides Range offers the largest area in the UK for the firing of rockets and missiles, including the Rapier-surface-to-air system.
The turbine proposals have already been subject to controversy after councillors went against planning officials’ advice to approve the schemes, claiming the MoD’s case against them was not robust.
The plans would have seen the turbines erected on the west coast of South Uist, but the MoD stressed that such developments would hinder its radars on the island, which serve the test site.
The Hebrides Range, which was set up in the 1950s, has sites on Benbecula, North and South Uist and a radar station on the remote St Kilda archipelago.
The MoD submitted the windfarms could interfere with air defence radar, showing up on the system as an aircraft, or resulting in “clutter”, which desensitises radar and increases the risk of a detection failure.
It claimed the risks arise when a certain level of proliferation of turbines in an area is exceeded.
In its submission to one of the planning applications for a turbine outside a croft on South Uist, the MoD stated that trials carried out in 2005 concluded that wind turbines can have “detrimental effects on the operation of radar”.
They added: “The probability of the radar detecting aircraft flying over or in the vicinity of the turbines would be reduced, and the RAF would be unable to provide a full air surveillance service in the area of the proposed wind farm.”
The council stated that “given the nature and size of the proposals,” the committee did not consider it had a “full understanding of the technical reasons” cited by the MoD as part of its objections.
At a meeting of the same committee in November, officials recommended that both 60kW and 50kW schemes be refused, warning that the turbines would cause “unacceptable interference” to the
MoD’s air defence radar systems and went against their own local development plan.
At the meeting, however, councillors disregarded the advice, approving the turbines, which have blade tip height of 26.6 metres and 19 metres respectively.
The decision ratified an amendment which stated that the MoD “had not demonstrated to the committee’s satisfaction that this development would have an adverse impact on defence”.
Keith Bray, the council’s head of development services, had warned councillors that the move would be “rather irresponsible as a planning authority”.
The other turbine subject to the proceedings, located further south on the island, was approved in January. The 10kW Frobost turbine will have a 15.1-metre blade tip height.