Defence giant BAE Systems is planning to axe more than 600 jobs and close a historic factory in Newcastle which made tanks for the First World War.
The firm said 330 jobs will be lost through the closure of the site, which is currently making Terrier vehicles for the Army.
The factory has been a defence manufacturing site since 1847, building a number of ships and employing tens of thousands of workers in its heyday.
Up to 280 jobs will also be lost at three BAE sites in Washington, Radway Green, near Crewe, and Glascoed in South Wales under the proposals, as well as the prospect of 10 job cuts at the firm's head office in Farnborough, Hampshire.
BAE said the proposal to close the Newcastle site at the end of 2013 followed a business review which concluded that there was no prospect of new UK armoured vehicle manufacturing work once production of the Terrier ends next year.
The firm said the proposals now under consultation followed major efficiency improvements and reductions in the amount of ammunitions required by the Ministry of Defence.
Managing director Charlie Blakemore said: "We need to adapt to very challenging market conditions and further reduce our overheads to drive better value for our customers and increase our competitiveness in the export market.
"I know that this is difficult news for employees and we will do all we can to help them through this difficult period and mitigate the proposed job losses wherever possible."