U.S. Vice President Kamala Harris will attend the international Ukraine Peace Summit in Switzerland this weekend, where she will meet with Ukrainian President Volodymyr Zelenskyy and address world leaders.

She will underscore that the outcome of the war with Russia affects the entire world, a U.S. official said, and push for a maximum number of countries to back the notion that Moscow’s invasion of Ukraine is a violation of the U.N. Charter’s founding principles and that Ukraine’s sovereignty and territorial integrity must be respected.

Harris, who will spend less than 24 hours at the gathering in Lucerne, Switzerland, will be standing in for President Joe Biden at the event. The president will be just ending his participation at the G7 summit in Italy and returning to the United States to attend a fundraiser for his reelection campaign in Los Angeles.

Harris will meet with Zelenskyy and will address the summit’s plenary session. Biden met Zelenskyy at the G7 summit, where they signed a U.S.-Ukraine bilateral security agreement, and in France for events surrounding the 80th anniversary of the D-Day invasion.

Harris was to depart for Switzerland on Friday night, arrive Saturday midday and spend several hours at the event before flying back to Washington.

Then, White House national security adviser Jake Sullivan will represent the United States at the summit on Sunday and help establish working groups on returning Ukrainian children from Russia and energy security.

Russia was not invited to the event and has dismissed it as futile. China, a key Russian ally, says it will not attend the conference because it does not meet Beijing’s requirements, including the participation of Russia.

The senior U.S. official said Russia’s absence would not affect the summit but expressed regret at Beijing’s decision.

Ninety-two countries and eight organizations plan to attend.

The United States has contributed billions of dollars in weaponry to help Ukraine fight the war begun by Russian President Vladimir Putin, although the latest massive package of aid from Washington was delayed for months by disagreements in Congress.