As the war of words and sanctions continues between Moscow and Ankara, Russian President Vladimir Putin has called on the U.K. to send aviation experts to Russia to examine the black box from the Su-24 jet shot down by Turkey in late November. The request comes as Russian Prime Minister Dmitry Medvedev told Russian media Wednesday that Turkey’s action had provided the justification to start a war.

“What did 20th century countries used to do in a similar situation? A war began,” Medvedev said, Kremlin-backed news organization RT reported. “That was a direct assault on a foreign state. In the present situation a war is the worst what could happen. That’s why a decision was taken not to give a symmetrical answer to what the Turks had done.”

Turkey last month shot down a Russian jet flying near the Syrian border, claiming the aircraft had violated the country’s sovereign airspace. The Kremlin has denied this allegation and showed satellite photos as evidence.

In a media move, Putin was presented with the black box late Tuesday, and the president asked his defense minister not to open the box until international experts were able to come and examine it. Two Russian servicemen were killed in the downing of the jet Nov. 24.

“As I understand, the flight data recorder will give us the opportunity to understand the Su-24’s trajectory from the moment of its takeoff to the moment of the crash,” Putin said.

In retaliation for the downing of the aircraft, Moscow has applied economic sanctions targeting Turkey’s tourism and agriculture sectors. Ankara said Tuesday it was considering its own retaliatory sanctions against Russia, Agence France-Presse reported.

“But we hope that the crisis with Russia will be overcome and there will be no need to resort to these measures,” Turkish Prime Minister Ahmet Davutoglu said. “We are ready for all kinds of discussions with Russia, but we will never accept being dictated to.”

Turkey has refused to apologize for shooting down the Russian jet, and the Kremlin continues to deny the aircraft entered Turkish airspace. Russia began conducting airstrikes in Syria at the end of September.