Crimea has formally asked to join Russia after voters overwhelmingly approved a referendum to secede from Ukraine. Crimean authorities say 96.8 percent of voters supported the referendum, but many members of the ethnic Ukrainian and Muslim Tatar minorities in Crimea stayed home in a boycott. The Obama administration has threatened sanctions on Russia if Crimea follows through and secedes. Russia has vowed to approve Crimea’s bid in a parliamentary vote. On Saturday, the Russian government vetoed a U.S.-backed Security Council resolution declaring the referendum invalid. Russia’s occupation of Crimea also sparked a massive opposition protest at home, with tens of thousands marching in Moscow on Saturday against military intervention in Crimea. It was Russia’s largest opposition rally since 2012. Tension meanwhile is rising in parts of eastern Ukraine that have seen a series of pro-Russian rallies. The Ukrainian parliament has endorsed a presidential decree for a partial military mobilization to call up 40,000 reservists to counter Russia’s military actions.