Rubio doubts 'anything productive' will happen in Ukraine peace talks without Trump, Putin

According to reports, frustration grew as the delegations and mediators spent much of the day questioning when, and even whether, they would meet on Thursday before the meeting was ultimately pushed to Friday.

"I don't think anything productive is actually going to happen from this point forward… until they engage in a very frank and direct conversation, which I know President Trump is willing to do," he added. 

The Kremlin on Thursday confirmed Putin was not going to participate in the peace talks. 

"Look, nothing's going to happen until Putin and I get together. OK?" Trump said. "He was going to go, but he thought I was going to go. He wasn't going if I wasn't there. 

"I don't believe anything's going to happen, whether you like it or not, until he and I get together," he added.

Any future plans for Trump and Putin to talk remain unknown.

Zelenskyy did not hold back in expressing his frustration over what he said is proof that Putin's "attitude is unserious."