NATO and Russia have agreed to meet Wednesday for talks on the crisis in Ukraine. That meeting, in Brussels, will be the first public contact between the Western defense alliance and Russia's envoys since its forces moved into Ukraine's Crimean peninsula late last week.
NATO announced the extraordinary session Tuesday, saying it was requested by Secretary-General Anders Fogh Rasmussen. The alliance offered no further details.
Members of NATO met earlier Tuesday at the request of Poland, which shares a border with Ukraine. Afterward, the alliance said the Russian military presence in Ukraine presents "serious implications for the security and stability of the Euro-Atlantic area."
In Washington Tuesday, U.S. President Barack Obama called on Russia to open talks with the interim Ukrainian government, and to allow international monitors to determine whether ethnic Russians in Ukraine are under threat, as alleged by Moscow.
Mr. Obama's comments followed a news conference in Moscow by Russian President Vladimir Putin, who defended his country's military intervention in Crimea.
The Russian leader said he reserves the right to protect Russians in Ukraine. But he also insisted that gunmen blocking Ukrainian military units in the region are "local self-defense forces," not Russian soldiers.
President Obama countered that Moscow has no legal right to intervene militarily, while acknowledging that Mr. Putin "seems to have a different set of lawyers making a different set of interpretations."
In Kyiv Tuesday, U.S. Secretary of State John Kerry also condemned Russian actions in Crimea and pledged U.S. economic help to the interim government. As he arrived in the capital, the Obama administration announced a $1 billion energy subsidy package for Ukraine, which is teetering on the brink of bankruptcy.
The U.S. diplomat spoke after meeting with Ukraine's top officials and visiting the site of a memorial to protesters killed in weeks of clashes with riot police. Those protests forced then-president Viktor Yanukovych to flee Ukraine in late February.
The Crimean peninsula was placed under Ukrainian control in 1954 by then-Soviet leader Nikita Khrushchev. It remained part of Ukraine when the Soviet Union collapsed in 1991. Crimea has a tiny border with Russia on its far eastern point, and the Crimean port of Sevastapol is home to Russia's Black Sea fleet.
Most residents of Crimea are ethnic Russians, but the region also is home to ethnic Muslim Tatars, who generally show disdain for Russia.
Ukrainian officials say Moscow has sent 16,000 troops into Crimea since last week.
Ukraine's troubles began in November, when President Yanukovych backed out of a trade deal with the European Union in favor of closer ties and economic aid from Russia. The move triggered weeks of pro-Western anti-government demonstrations in Kyiv and elsewhere in Ukraine, and forced the pro-Russian Yanukovych to flee the capital in late February.