Britain's Science Minister Sam Gyimah resigned late on Friday branding Prime Minister Theresa May "incredibly naive" after she announced the UK would not be involved in the EU's Galileo project post-Brexit.
The UK had wanted to stay part of the €10 billion project to develop a global navigation satellite system to rival the US but the EU said the country would be banned from using the encrypted, more secure features of the system, designed to be used by govermental entities.
May confirmed on Friday that the UK was pulling out of the project.
"The commission decided that we would be barred from having full aspects of the Galileo programme and so it is right for us to look for alternatives." May told reporters in Buenos Aires where she is attending the G20 summit.
"I cannot let our armed services depend on a system that we cannot be sure of. That would not be in our national interest," she added.
Britain's Universities and Sciences Minister Sam Gyimah responded to the announcement by offering his resignation.
"Galileo is a clarion call that it will be the 'Eu first', and to think otherwise — whether you are a leaver or a remainer — is at best incredibly naive," Gyimah wrote in a statement on Facebook.
"In these protacted negotiations our interests will be repeatedly and permanently hammered by the EU27 for many years to come," he added.
He is the 10th minister to resign since May released her Chequers' Plan for Brexit in July.
Gyimah also announced that he will be voting against the Withdrawal Agreement on December 11. If British MPs reject May's draft Brexit deal the UK is then likely to crash out of the EU without a deal.
May has called for MPs to back her agreement with the bloc as it would trigger a 18-months transition period, during which the UK would still be able to enjoy the benefits of EU membership — it will however be excluded from the decision-making process — while negotiations continue.
But she faces an uphill battle. Like Gyimah, many others in her Conservative party have said they would defy her. Northern Ireland's Democratic Unionist Party, whose support May's minority government relies on to pass legislation, has also signalled it would oppose the deal.
Opposition parties including Labour, the Scottish National Party and the Liberal Democrats, have also said they would vote against the agreement.
First agreed upon in 2003, Galileo is expected to be fully deployed in 2020.
The Navigation Satellite System is meant to improve GPS services on the Old continent and end the reliance on US, Russian and Chinese systems.
It is intended to be used by civilians, commercial endeavours, governments and the military.
Back in August, the UK said it would set up its own system should it be excluded from Galileo and set aside £92 million (€103) for the UK Space Agency to study an alternative.
The UK spent over €1 billion on the development of Galileo. It is unclear yet if it will recoup the money.