U.S. President Joe Biden will reaffirm Washington's support for Ukraine’s sovereignty in the face of a Russian military buildup when he holds a video call with President Vladimir Putin on Tuesday, according to a White House statement.

The diplomatic effort, which the Kremlin announced earlier Saturday, follows weeks of escalating tension over Russian encroachment on its neighbor. A senior administration official said Friday that U.S. intelligence had concluded the Kremlin was planning an offensive against Ukraine as soon as next year involving an estimated 175,000 personnel.

"President Biden will underscore U.S. concerns with Russian military activities on the border with Ukraine and reaffirm the United States’ support for the sovereignty and territorial integrity of Ukraine,” White House spokeswoman Jen Psaki said in the statement.