On Saturday, the Evening Times revealed work is starting to dismantle the landmark cranes at Govan shipyard, leading to mounting speculation that the yard could be closed.
When the current work runs out, the workforce at both Govan and BAE's sister yard in Scotstoun is pinning its hopes on the Type 26 frigates contract coming to the Clyde.
A decision is expected as early as this month, but until then thousands of workers face an uncertain future.
It is expected that a reduction in workload will see the workforce halved from around 3000 to 1500, but whether they will be based at both Govan and Scotstoun or just a single Clyde yard is unclear.
Closure of the Govan yard would have a serious economic impact on the surrounding area with many local businesses dependent on the yard's workforce for their custom.
Jim Moohan of the GMB union is chairman of the Confederation of Shipbuilding and Engineering Unions.
He said the UK Government has to make the announcement to allow BAE to plan its investment and let the workers know their future.
Mr Moohan said: "There has been speculation for some time now in relation to the long-term future of the shipyards. We are waiting for the MoD through BAE to confirm what the long-term strategy is.
"It does create a cloud of uncertainty and in the background we are aware big changes are afoot
"But the MoD and the Government have to come clean very soon."
Previously, workers at the yards have been laid off because of gaps in the order book despite it being known work is coming.
Mr Moohan said that needs to be avoided and continuity is crucial for workforce retention.
He said: "It is important the Type 26 order is placed to run parallel with current workload.
"The workers have been loyal and committed for the past 12 years and BAE has invested in infrastructure and skills in both Clyde yards.
"BAE has done the best it can to protect jobs up to the present time and is spending money in the hope the order comes through.
"But, whether it is for three or six ships, we hope the announcement from the MoD is soon to allow BAE to plan."
The speculation centres on the Type 26 order coming to the Clyde, but BAE only being able to guarantee enough future work for one yard, and the union is braced for a good-news, bad-news announcement.
Mr Moohan said: "We know there is going to be a sting in the tail. If they can't retain two yards then what can they retain?
"BAE is committed as best it can, but now we need the Government to give the go ahead.
"It is not only the workers at Govan and Scotstoun. There are thousands employed in hundreds of firms supplying shipyards and sub-contractors working in the yards who rely on BAE.
"This is of vital importance for Scottish Manufacturing.
"We want the Government to advise BAE so it can plan and advise the workers on their future."
The decommissioning of the cranes is feared to be a sign that Govan could be about to lose out.
The five dockside portal cranes, a Glasgow landmark, are owned by Clydeport which also owns the shipyard land, while BAE owns the yard at Scotstoun.
Clydeport is removing the cranes at the request of BAE, which said the timing is not connected to the imminent decision to close one of its three yards, with Portsmouth also under threat.
Politicians in the city are looking for clarity from the company on the future of the yards.
Margaret Curran, Shadow Scottish Secretary, said: "The Govan yard is a vital source of employment for people in Glasgow and the Clyde valley and it is essential that we secure its long-term future.
"I will be asking to meet with BAE to get to the bottom of these reports."
Nicola Sturgeon, Deputy First Minister, and Glasgow Southside MSP, urged the company not to dismantle the cranes until an announcement was made.
She said: "I would hope the decision to take down the cranes would be put on hold until a decision on the future of the yards is made. I don't want to see Govan shipyard close."