The U.S. carried out an "extraordinary" flight over Ukraine Thursday days after Russia seized three Ukrainian naval ships off Crimea. Citing the Open Skies Treaty, the Pentagon said the U.S. and allies conducted the flight "to reaffirm U.S. commitment to Ukraine and other partner nations.‎"

"Russia's unprovoked attack on Ukrainian naval vessels in the Black Sea near the Kerch Strait is a dangerous escalation in a pattern of increasingly provocative and threatening activity," the Pentagon said in a statement.

"The United States seeks a better relationship with Russia, but this cannot happen while its unlawful and destabilizing actions continue in Ukraine and elsewhere."

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Russia blamed Ukraine for provoking the incident, which sharply escalated tensions that have been growing between the two countries since Moscow annexed Crimea from Ukraine in 2014, and it has worked steadily to bolster its zone of control around the peninsula.