Former Defense Secretary Mark Esper said on Wednesday that it is "unlikely but possible" that Russian President Vladimir Putin will deploy nuclear weapons in Ukraine.
"The more that Ukraine has continued to seize ground in the east and in the south, I think the more desperate Putin becomes," Esper told CNN. "This has been a strategic failure in multiple ways since it began in February. … I think Putin continues to paint himself in a corner and limiting his options to get out of this mess he's created."
Esper estimated that if Russia were to use a nuclear weapon, it would likely be between 1 and 10 kilotons. For reference, he noted that the 15-kiloton nuclear weapon that the U.S. used in Hiroshima, Japan, killed 70,000 people and destroyed five square miles of territory.
He said the U.S. and its allies could respond to the heightened threat by communicating to Moscow that if there is any indication they plan to use a "tactical" nuclear weapon, they will put an air cap above Ukraine and shoot down anything that could be carrying a nuclear weapon.
Putin has ratcheted up his nuclear rhetoric in recent weeks, as Russian forces have been forced to retreat from parts of eastern and southern Ukraine. Just a day after Putin announced the formal annexation of four Ukrainian regions, Russian forces withdrew from the city of Lyman in the Donetsk region - one of the four annexed territories - after Ukrainian forces surrounded the city.
Ukrainian President Volodymyr Zelensky, who dismissed Putin's earlier nuclear threats as bluffs, has warned that the Russian president's latest threats "could be a reality."
The country's capital city of Kyiv has begun prepping evacuations centers in the case of a potential nuclear attack, complete with potassium iodine pills to help against radiation absorption.
For the latest news, weather, sports, and streaming video, head to The Hill.