The UK's original plans provided for the full withdrawal of troops by 2020, but Williamson's order stipulates that 200 UK servicemen and their family members will remain in Germany after this deadline, The Sunday Times newspaper reported.
The UK will also keep its Sennelager base in northwestern Germany, which is intended for practicing tank warfare and large-scale maneuvers.
Besides this, London also plans to maintain a facility for armored vehicles in the city of Monchengladbach.
The sources in the UK Defense Ministry explained that Williamson's order should demonstrate to Russia that the United Kingdom will continue to defend Europe even after Brexit.
The United Kingdom voted to leave the European Union in June 2016, with the negotiations between the two parties expected to last until March 29, 2019.