The Labour party has urged ministers to give greater protection to UK jobs by favouring British defence manufacturers.
More than £6bn of spending recently set out by the Government will be spent on surveillance aircraft from overseas, according to Labour analysis.
But the Ministry of Defence (MOD) defended its approach, arguing it will see a move from global competition to boost British manufacturing.
Labour leader Sir Keir Starmer was backing a "British-built default" approach, rather than an "open competition" policy that sees off-the-shelf equipment bought from abroad.
"Prioritising British businesses through defence spending is not only investment in jobs, but in our communities, and a more secure economy," Sir Keir said.
Shadow defence secretary John Healey added: "Of course, there will be essential equipment or systems which makes strategic sense for Britain to develop with allies or to buy direct from overseas, but we want to see a much higher bar for this.
"When done well, defence spending has a multiplier effect, strengthening our UK economy.
"COVID has exposed the risks of relying on foreign supply chains.
"Labour's 'British by default' policy would strengthen the UK's sovereignty and security," he added.
"We would never compromise trying to get the best kit that our Armed Forces need," Mr Healey told Forces News.
"The failures of the last decade too often have left no option available, because the work hasn't been done to support the capacity and the development in the UK.
"Too often the option has been only to outsource overseas," the Shadow Defence Secretary added.
Sir Keir backed the call ahead of a defence-related visit to Plymouth on Wednesday.
An MOD spokeswoman said: "Our new Defence and Security Industrial Strategy will ensure home-grown skills and enterprise are fully harnessed as we move away from global competition by default and lean towards British built to boost manufacturing within the UK supply chain.
"Combined with a commitment to spend £85 billion on equipment over the next four years, defence will generate and sustain thousands of highly skilled jobs, driving prosperity throughout the country."
While for the RAF, it was announced £2bn will be invested over the next four years into the Tempest programme, which plans for a sixth-generation fighter jet by 2035, as well as developing the LANCA (Lightweight Affordable Novel Combat Aircraft) capability.
Cover image: Manufacturer BAE Systems facility at Barrow-in-Furness.