Kushner, acting for Netanyahu, asked Flynn to contact each delegate from the various countries on the Security Council to delay or kill the resolution. Flynn agreed to do so, which included the call to the Russians. Kislyak took the call but did not agree to veto Security Council Resolution 2334, which passed unanimously on December 23rd.
What exactly did Kushner seek from Flynn? He asked the soon-to-be National Security Adviser to get the Russians to undermine and subvert what was being done by the still-in-power American government in Washington headed by President Barack Obama. In legal terms this does not quite equate to the Constitution’s definition of treason since Israel is not technically an enemy, but it most certainly could be construed as covered by the “conspiracy against the United States” statute that Special Counsel Robert Mueller exploited in his investigations.