Several Republican senators walked out of a classified briefing on Ukraine Tuesday as it descended into a row over the border crisis, after President Volodymyr Zelensky unexpectedly canceled a videolink appearance to appeal for continued US funding. Zelensky had been due to update the senators on the latest developments in the conflict with Russia and press for them to support a procedural vote expected Wednesday on an emergency aid package that includes more than $60 billion for Kyiv. The cash has been held up for weeks by a row in Congress, as the White House has warned that existing funds will run out by the end of the year and that Russia's President Vladimir Putin could win the war if lawmakers fail to act. Congress is more divided over backing for Ukraine than it has been at any time during the nearly two-year conflict, with the country fast exhausting the military aid provided by the United States so far. Senate Republicans are making their support for extra Ukraine funding contingent on President Joe Biden's Democrats accepting reforms of the asylum system and tightened border security -- measures the Democrats have already rejected. As US senators square off at Ukraine briefing, FRANCE 24's Tom Burges Watson is joined by Anna Borshchevskaya, Senior Fellow in The Washington Institute's Diane and Guilford Glazer Foundation Program on Great Power Competition and the Middle East, focusing on Russia's policy toward the Middle East.