U.S. President Joe Biden has communicated his concerns about Russia's military buildup near Ukraine directly with Russian President Vladimir Putin, as well as the U.S. commitment to Ukraine's territorial integrity, White House national security adviser Jake Sullivan said on Wednesday.
"That's what we intend to do going forward but we intend to do that through high-level diplomatic communication, not through issuing public ultimatums," Sullivan said in an interview with MSNBC.
(Reporting by Doina Chiacu; Editing by Tim Ahmann)
