The Ukrainian military is taking Putin's threats seriously.
The Russian president made a thinly-veiled threat of nuclear warfare last week, warning that he was not bluffing.
In an interview with The Guardian this week, Vadym Skibitsky, Ukraine's deputy intelligence chief, put the threat of Russia using a nuclear weapon against Ukraine at a higher level.
Skibitsky said that they would likely target places along the frontlines with a lot of personal and equipment. We need anti-rocket systems to stop them.
The Ukrainian military intelligence boss did not provide evidence for his claims, and officials in his organization have spread baseless theories. As of Thursday, there were no signs that Russia had changed the location of its nukes, despite reports that it had.
The risk of Putin using a nuclear weapon has been raised by some Russia watchers. Russia's Foreign Minister said recently that any territory formally incorporated into Russia will be protected by the Kremlin.
Kevin Ryan, a retired US Army brigadier general, said in a recent interview that the red lines against fighting on Russian territory will be suddenly crossed. The Russian state will be attacked directly. Many analysts think that Putin's nuclear threats are designed to limit Western support for Ukraine.
"Putin's threats of escalation, including his implicit threat of nuclear escalation, are an attempt to frighten the West and deter it from continuing to armUkraine by using the false myth that the Kremlin leader is most dangerous when he is cornered." A senior fellow at the Atlantic Council's Eurasia Center wrote recently that the United States and its allies shouldn't fall for this ruse.
There is skepticism about Russia's ability to pull off a nuclear strike.
George Barros is a military analyst with the Institute for the Study of War.
"I don't think the Russian military is capable of doing that at the moment," Barros said.