Ukrainian soldiers have fought day after day to keep control of Bakhmut, a city in the east that military analysts say is not strategically important. President Volodymyr Zelenskyy has warned of the necessity of beating back the Russian forces besieging the city. He says, otherwise, Ukrainians could be forced to make unacceptable compromises.

Ukrainian units have been defending Bakhmut since August. Zelenskyy visited troops near the city last week and told reporters with the Associated Press that Russian President Vladimir Putin would use its capture for propaganda purposes.

Zelenskyy said, "He will sell this victory. He will sell this victory to West, to his society, to China, to Iran, to all the countries."

On Wednesday, Russian Foreign Minister Sergey Lavrov discussed how to end the fighting in talks with his Iranian counterpart, Hossein Amir-Abdollahian, in Moscow.

However, Putin's spokesperson Dmitry Peskov has suggested resolving the conflict will take a "very long time." The war in Ukraine reaches its 400th day on Thursday.

Russian forces in Siberia are preparing for such an outcome. They mobilized missile launchers on Wednesday for drills that underscored their nuclear threat.

Russian leaders say they will no longer warn US officials about any missile tests, as envisioned in a nuclear pact they have suspended.