President Biden cast the United Nations General Assembly gathering Tuesday as “darkened by the shadow” of the war in Ukraine for the second year, blaming Russia for its brutalization and lack of a resolution in the war torn country.

Biden reiterated his call to rally the international community in support of Ukraine as his administration urges Congress to provide additional support for Kyiv as it fends off invading Russian forces while warning other nations of their security.

“Russia believes that the world will grow weary and allow it to brutalize Ukraine without consequence,” Biden said in remarks from New York. “But I ask you this: If we abandon the core principles of the U.N. Charter to appease an aggressor, can any member state feel confident that they are protected?”

“If we allow Ukraine to be carved up, is the independence of any nation secure?” he said. “I respectfully suggest the answer is no. We must stand up to this naked aggression today to deter other would-be aggressors tomorrow.”

Ukrainian President Volodymyr Zelensky was looking on from the audience during the remarks.

“That is why the United States together with our allies and partners around the world will continue to stand with the brave people of Ukraine as they defend their sovereignty and territorial integrity — and their freedom,” Biden said, drawing applause from those inside the room.

Biden will host Zelensky at the White House Thursday. The Ukrainian president’s stop in Washington comes as the Biden administration pushes for Congress to approve $24 billion in additional funding for Ukraine in its war effort against Russia.

The U.S. has provided billions of dollars in military, financial and humanitarian assistance to Ukraine since the start of the war in February 2022, and the Biden administration has requested billions more as part of its latest supplemental funding package.

While there is still bipartisan support for Ukraine aid, some Republicans have pushed back on continued assistance for the country. And leading Republican presidential candidates, including former President Trump, have expressed skepticism about providing ongoing assistance to Ukraine.

The president, in his remarks Tuesday, also made clear that his approach to China is “for de-risking, not decoupling” and that the United Nations needs to work with China on issues like the climate crisis.

He highlighted impacts of the climate crisis, including drought in Africa, flooding in Libya, and heatwaves and wildfires in North America.

Biden also called for some reforms to the United Nations, including breaking gridlock in decision-making and bringing in more voices to improve the group.

“Simply put, the 21st century results are badly needed, they’re needed to move us along. That starts with the United Nations, starts right here in this room,” the president said.

His speech opened with a message of unity and the U.S. commitment to the United Nations.

“The United States seeks a more secure, more prosperous, more equitable world for all people, because we know our future is bound up with yours,” he said. “And no nation can meet the challenges of today alone.”