An announcement on the fate of the MoD firing range in Uist is expected to be made later.
Scottish Secretary Jim Murphy has told workers at the missile range on Uist the UK government has abandoned plans to close the site.
At the weekend, an advert was posted for a project manager to "dismantle" the site, but the MoD said no decision had been made.
His announcement was greeted by cheers from the 125 staff of contractor QinetiQ - who had faced jobs cuts.
The Western Isles base is operated for the MoD by private contractor QinetiQ.
The UK government had been warned that closing the site - the island's largest private employer - would collapse the local economy.
A proposal to modernise the facility with the loss of 125 jobs has been accepted in principle by the MoD and put out to consultation.
The Western Isles base is operated for the Ministry of Defence by QinetiQ.
Scottish Secretary Jim Murphy held talks with Defence Secretary Bob Ainsworth on Monday and is due to fly to Uist to meet staff at the range.
Remote operation
The job advert - which has been posted internally on QinetiQ's website - was met with an angry reaction from Western Isles MSP Alasdair Allan on Monday.
The SNP MSP pledged to seek answers at Holyrood, and said: "It is very difficult to read this job advert any other way: QinetiQ, it seems, are looking for someone who will oversee the dismantling of the command and control functions at Hebrides Range, leading to the operation of much of its activities by remote control from Aberporth in Wales.
Scottish Secretary Jim Murphy is expected to brief staff on Tuesday
"How does that square with all the protestations from QinetiQ, the MoD and the Secretary of State for Scotland that they are genuinely listening?"
The proposed modernisation of the range would see 125 of 215 jobs cut as a result of the radar station on Hirta in St Kilda being operated remotely, with staff only visiting for maintenance and servicing.
The command and control centre on South Uist has been earmarked for closure by 2014. Rocket trials would run instead from Aberporth in Wales using new technology.
West Camp - an army base at Balivanich, Benbecula - would remain open but one accommodation block would close, reducing the need for domestic staff.
The camp is linked to training on the Rapier air defence missile system which is used by the Royal Artillery and RAF.
On Monday an MoD spokeswoman said no decision had been made on the base's future, but that an announcement would likely be made within the next week.
