Russian President Vladimir Putin appears poised to escalate his nearly five-year war against Ukraine, even as casualties mount, frustration grows inside Russia and NATO allies become increasingly alarmed about what Moscow could do next, The Economist reported.

Putin has shown no indication he is prepared to retreat from the conflict despite Russia’s failure to achieve a decisive battlefield victory and increasingly successful Ukrainian drone attacks deep inside Russian territory, according to the magazine.

Speaking Saturday to students and staff at a Moscow university, Putin compared international conflict to the natural world’s food chain while defending his invasion of Ukraine.

“That’s the food chain,” Putin said after claiming that orcas feed on polar bears. “Children should be taught about this, so that they understand what kind of world we live in and why we are conducting the special military operation.”

The Economist noted there are no known cases of orcas eating polar bears.

Putin has also stepped up his rhetoric after Ukrainian drones struck Russian oil refineries, logistics centers, and other key facilities.

Ukraine opened a “Pandora’s box,” Putin warned Aug. 22, promising “blowback on the most sensitive sectors of your economy.”

Putin made clear the same day that Moscow has no intention of ending the fighting.

“The special military operation continues,” Putin told members of his United Russia party. “We will move only forward.”

Sources close to the Kremlin told The Economist that Putin spent several weeks weighing his options this summer before apparently deciding to escalate.

That prospect is raising alarms across NATO.

CIA Director John Ratcliffe secretly traveled to Moscow on Aug. 25. There are conflicting reports over whether Ratcliffe went to warn Putin against attacking NATO countries or to press him toward negotiations by delivering a bleak assessment of Russia’s military prospects.

Finland subsequently requested Swedish aircraft and warships to help monitor its Russian border. Germany is preparing to blame Moscow for an Aug. 4 drone attack at Leipzig’s airport, while Romania said it destroyed a Russian naval drone targeting a drilling platform in its waters, according to the magazine.

Putin also faces mounting pressure at home.

The Levada Centre, an independent pollster, found 57% of Russians describe conditions in the country as “tense,” citing the war, casualties, mobilization, drone attacks, and uncertainty about the future, The Economist reported.

Frustration is also spreading among Russia’s elites, according to the magazine, as the Kremlin approaches five years of war without achieving its major objectives.

Putin, however, could view backing down as a threat to his own survival. The Economist reported he may believe ending the war without capturing all of Ukraine’s eastern Donbas region would endanger his grip on power.

“They will hang me,” Putin told associates at one point during the war.

Western intelligence agencies are concerned Moscow could intensify sabotage and other hybrid attacks against Ukraine’s European allies, including factories producing military equipment for Kyiv.

Those agencies reportedly do not believe Putin wants a direct war with NATO.

Meanwhile, Russia’s Defense Ministry said Sunday it was preparing a massive strike against Ukraine’s energy infrastructure.

Russian sources also told The Economist that Putin is prepared to throw another 300,000 to 400,000 troops into the war, potentially relying on regional governments to boost recruitment without announcing another nationwide mobilization.