President Barack Obama and his Russian counterpart, President Vladimir Putin, strongly disagree over what's at stake in the Ukraine crisis.
Those differing views were made clear in a 90-minute phone call and could make it difficult to find a resolution to the crisis in Ukraine.
In the Saturday call, Obama called Russia's actions "a clear violation of Ukrainian sovereignty." President Putin responded that the turmoil in Ukraine posed real threats to the life and health of Russian citizens living in Ukraine.
Russian troops took over Crimea as the Russian parliament on Saturday granted Putin authority to use the military to protect Russian interests in Ukraine.