Putin, Biden to speak again over NATO, Ukraine, Russian border troop buildup

President Biden and Vladimir Putin will speak Thursday amid the Russian leader's demands for security guarantees in Eastern Europe as NATO considers allowing Ukraine to join the group. 

The two leaders will discuss "a range of topics, including upcoming diplomatic engagements," National Security Council spokeswoman Emily Horne said Wednesday, according to the Associated Press. They met face to face in June in Switzerland.

Putin has assembled an estimated 100,000 troops along the Russia-Ukraine border, in apparent opposition to the North Atlantic Treaty Organization allowing in Ukraine, which belonged to the former Soviet Union. 

The troop buildup along the border has also stoked fears that Putin is so opposed to such a NATO move that he's prepared to invade Ukraine.

Secretary of State Antony Blinken spoke on Wednesday with Ukrainian President Volodymyr Zelenskyy and "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," the wire service also reports.

Putin said earlier this week he would consider several options if the West fails to meet his demand 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.