REHOBOTH BEACH, Del — President Joe Biden and Vladimir Putin will speak Thursday as the Russian leader has stepped up his demands for security guarantees in Eastern Europe.

The two leaders will discuss “a range of topics, including upcoming diplomatic engagements,” National Security Council spokeswoman Emily Horne said in a statement announcing the call.

The talks come as the U.S. and Western allies have watched the buildup of Russian troops near the border of Ukraine, growing to an estimated 100,000 and fueling fears that Moscow is preparing to invade Ukraine.

Secretary of State Antony Blinken spoke on Wednesday with Ukrainian President Volodymyr Zelenskyy.

State Department spokesman Ned Price said Blinken “reiterated the United States’ unwavering support for Ukraine’s independence, sovereignty, and territorial integrity in the face of Russia’s military buildup on Ukraine’s borders.”

Price said the two discussed efforts to peacefully resolve the conflict in eastern Ukraine and upcoming diplomatic engagements with Russia.

Putin said earlier this week he would ponder a slew of options if the West fails to meet his push for security guarantees precluding NATO’s expansion to Ukraine.

Earlier this month, Moscow submitted draft security documents demanding that NATO deny membership to Ukraine and other former Soviet countries and roll back its military deployments in Central and Eastern Europe.