President Joe Biden and Ukrainian President Volodymyr Zelenskyy spoke before the United Nations on Tuesday to stress the need to maintain support for Ukraine as it fights against Russia’s invasion.

President Biden told the U.N. General Assembly that Russia was banking on the world growing weary of the war to allow it “to brutalize Ukraine without consequence.”

He then asked a pointed question.

“If we abandon the core principles of the United States to appease an oppressor, can any member staying in this body feel confident that they are protected?” asked Biden. “If we allow Ukraine to be carved up is the independence of any nation secure?”

Meanwhile, Zelenskyy called for unity in the face of Russian aggression.

“We must act united to defeat the aggressor and focus all our capabilities and our energy on addressing these challenges,” he said. “For the first time in modern history we have a real chance to end the aggression on the terms of the nation which was attacked.”

In an interview with WTTW News, former Ukrainian President Viktor Yushchenko, who is in Chicago to commemorate the Holodomor – a genocidal famine imposed by Stalin’s Russia that killed millions of Ukrainians from 1932 to 1933 – gave an assessment of the challenges Zelenskyy faces.

Former First Lady Kateryna Yushchenko translated her husband’s answers.

Yushchenko was poisoned and almost lost his life in 2004 as he ran for the presidency on a pro-West and pro-democracy platform.

Most observers believe the assassination attempt was at Russian President Vladimir Putin’s direction as he sought to maintain Russia’s influence in Ukraine.

Yushchenko spoke about Ukraine’s desire to embrace Europe and NATO.