Khodorkovsky, a prominent critic of the Russian leader, previously spent a decade in prison in Russia on charges widely regarded as revenge for challenging Putin's rule. Russian troops began their invasion of Ukraine on February 24.

Putin announced that the operation aimed at "demilitarizing" and "de-nazifying" the former Soviet state and protecting Russian speakers in the country. But with Russia failing to quickly occupy the country due to strong Ukrainian resistance and its troops getting bogged down, Moscow recently announced a change in its war aims, saying that it will focus on the "liberation" of the Donbas region in eastern Ukraine.

"Putin is stuck when it comes to the military operation," Khodorkovsky said, adding, "Putin has two options now: Either he escalates things, which could mean either introducing mobilization or using tactical nuclear weapons, or he can stabilize the situation and begin peace talks in earnest."

In the interview with DW, Khodorkovsky also stressed the importance of a unified Western position. "The West's position needs to be clear, meaning comprehensive support for Ukraine if the war continues and in case Putin uses tactical nuclear weapons or other weapons of mass destruction," he underlined. "That sort of clear position from the West will, let's say, help Putin make the right decision."