Russia has proposed another attempt at peace negotiations with Ukraine on Monday in Istanbul, but both sides remain firmly entrenched in positions likely to prolong the war.

There are lots of unknowns ahead of potential direct talks between Russia and Ukraine in Turkey.

Russia declared a three-day ceasefire in Ukraine starting May 8 for the anniversary of the Soviet Union's victory over Nazi Germany. Ukraine called for an immediate, 30-day truce instead.

The U.S. is showing signs that it is increasingly willing to withdraw from a peace process that has grown more complex in recent months.

A roundup of key developments and the latest in-depth coverage of Russia's invasion of Ukraine.

The historic negotiations represent the first direct talks between the long-warring sides. However, leaders warn that reaching a peace deal could take time.