Yoshiko Herrera is a political science professor at UW-Madison. 

She studies Russian politics and international relations. 

Herrera said Russia's invasion of Ukraine has been brutally violent. 

"It's been a very destructive war. There's estimates recently of maybe 15,000 casualties on each side," Herrera said. 

She said it's tough to guess on what the end-game of the war looks like. 

"Ukrainians are committed to to maintaining their state, and Putin is committed to continued brutality," Herrera said. 

She said economic sanctions from the U.S. and the west have shrunk the Russian economy by roughly seven percent. 

"But Russia continues to sell oil and gas, even to Europe, and that continues to bring in billions of dollars to the regime," Herrera said. "Further energy sanctions, while they would have a severe effect on Europe, they probably would end the war pretty quickly." 

"The reliance on selling energy, that's what is keeping the Russian government afloat right now," she said.