Art Cashin, UBS director of floor operations at the NYSE, said weakness in Europe weighed on U.S. stocks this morning, which have bounced back since major averages closed across the pond.
"It's very clear a sigh of relief here when Europe closed," Cashin said.
Trading has been choppy Tuesday with markets digesting another crash in crude oil prices and downbeat news about the global economy. European markets closed at session lows after the European Commission lowered its growth outlook for the euro area and warned inflation will be below the European Central Banks's (ECB) prediction.
Read MoreEuropean shares extend losses after report on challenge to Draghi
"The ball is clearly in Europe's court," said Cashin. "Draghi's got to do something."
Europe's bond market is different than that of the U.S. because it does not have a single, fluid structure; therefore, replicating the stimulus, or QE, the U.S. employed will be difficult.
Cashin explained countries may question Draghi's strategy if he starts picking and choosing which sovereign bonds to buy over others.
"It's an uphill fight," added Cashin.
—By CNBC's Kristen Scholer.