Klobuchar says she was 'appalled' by Trump and Zelenskyy shouting match

Sen. Amy Klobuchar backed Ukrainian President Volodymyr Zelenskyy on Sunday after the volatile White House meeting with President Donald Trump on Friday, saying she "just couldn't believe” how Friday’s meeting unfolded..

The Minnesota Democrat told ABC News' "This Week" anchor George Stephanopoulos she was "appalled by what happened in the Oval Office," and thinks the fallout of the exchange "is not in President Trump's best interest."

"We stand with our friends, not our enemies," Klobuchar said. "The great country of America goes into negotiations with strength, not surrender."

Klobuchar said she -- along with other senators from both sides of the aisle -- had been with Zelenskyy before he left for the White House, and said he had been in "great spirits."

Watching video of the explosive meeting, Klobuchar said she "just couldn't believe it."

"It was Vice President Vance, particularly, who was on the offense, who was berating President Zelenskyy, who simply was trying to explain that ... we needed a strong security commitment from all of our allies to be able to have a lasting peace, which is something that President Trump says that he wants to see."

Klobuchar speculated on how the meeting so quickly became caustic when asked by Stephanopoulos if it had been an ambush.

"Either it was an ambush setup, or they just got so hotheaded, the president and the vice president, that what happened happened," she said. "It's the chaos of this presidency."

Meanwhile, British ambassador to the U.S. Lord Peter Mandelson said the U.S.-Ukraine relationship needs a "reset" after the Trump-Zelenskyy meeting.

"I think that Ukraine should be the first to commit to a ceasefire and defy the Russians to follow," Mandelson told Stephanopoulos. "And then, as part of the unfolding plan for this negotiation, the Europeans and perhaps some other countries too, have got to consider how they are going to put forces on the ground to play their part in providing enduring security and deterrence for Ukraine."

European leaders were meeting in London on Sunday to discuss a UK-French peace plan they're working on with Zelenskyy that they plan to present to the U.S.

Mandelson said it will be important to "create the circumstances in which enough pressure is brought on" to "force [Russia] to the negotiating table."

"And then we will see the true color of their intentions and what they're prepared to agree and to stand by," he said. "But if it goes wrong, we must be there on Ukraine's side, continuing to arm them to make sure that they have the capacity to withstand any further Russian attack with ourselves lining up behind them in that eventuality."