The U.K. imposed further sanctions on Russia for its attack on Ukraine on Thursday as the war prepared to roll into its second month. Last week, concern over possible chemical weapon attacks heightened. The U.K. issued 65 sanctions, including travel bans and asset freezes on the Wagner Group, a Russian private military company that was at one point allegedly given the job of assassinating Ukrainian President Volodymyr Zelensky. The group has an estimated 6,000 members, made up mostly of retired Russian soldiers. Though it works with Russia and many see it as Russian President Vladimir Putin's personal army, it is not technically affiliated with any country. The group is believed to be owned by Russian businessman Yevgeny Prigozhin, though he claimed that he had no connection to the group. "We've got to tighten the economic vice around Putin, sanctioning more people today, as we are, sanctioning the Wagner Group, looking at what we can do to stop Putin using his gold reserves, and also doing more to help the Ukrainians defend themselves," said U.K. Prime Minister Boris Johnson. Some of the other sanctions affected drone builder Kronshtadt, billionaire Eugene Shvidler and Tinkoff bank founder Oleg Tinkov. "Putin should be under no illusions – we are united with our allies and will keep tightening the screw on the Russian economy to help ensure he fails in Ukraine," said U.K. Foreign Secretary Lizz Truss. "There will be no let-up."