U.S. Deputy Secretary of State Wendy Sherman said Tuesday that Russian troops appeared to be “on the ropes” in Ukraine and that the Kremlin’s actions, including what she called “fake referendums” in some regions of Ukraine, were a desperate move by the president. Vladimir Putin, reports CNN.

In an interview with MSNBC, Sherman said there was concern that Putin would “use weapons of war that he shouldn’t be using,” noting that he has already used food as a weapon.

“Let’s hope he understands what the president just told him: don’t do it. No. No,” she said, referring to President Joe Biden’s warning about a response if Russia uses chemical or nuclear weapons.

Several Kremlin-backed authorities in eastern and southern Ukraine have announced that referendums on joining Russia will be held this week. Ukraine rejected this step as “fear of defeat”.