The energy giant is spending nearly $50 billion to expand the Tengiz oil field, allowing it to pump one million barrels a day.

President Vladimir V. Putin of Russia told the Azerbaijani leader, Ilham Aliyev, in a phone call, “that the tragic incident took place in Russian airspace.”

Flight attendants and a passenger described the moments before an Azerbaijan Airlines flight went down in Kazakhstan, killing dozens.

Russian aviation authorities said the Azerbaijan Airlines plane had hit a flock of birds. But some experts cast doubt on that account, pointing to footage showing apparent holes in the fuselage.