On Friday, in a ceremony at the Kremlin, Russian President Vladimir Putin proclaimed the annexation of four regions of Ukraine: Luhansk, Donetsk, Kherson, and Zaporizhzhia. These regions make up about 15-percent of Ukrainian territory.

The announcement was resoundingly condemned as illegal and illegitimate by the the international community. A day after the announcement, Ukraine liberated the Donetsk city of Lyman, forcing Russian troops to retreat in another humiliating defeat in recent weeks.

We speak with Ambassador Michael McFaul, former U.S. Ambassador to Russia and professor of international studies at Stanford, about how Russia’s annexation announcement changes the war, and what this announcement means for growing tensions between the U.S. and Russia.