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The NATO secretary general noted that Putin reacts to defeats with "greater brutality," therefore, Russia began to attack Ukraine's energy system.
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"Putin is trying to use winter as a weapon," he said.
"But he will not achieve this success."
According to Stoltenberg, Ukraine's greater military successes on the battlefield will make the Ukrainian government's position stronger in future peace negotiations.
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"We can strengthen Ukraine's position at the negotiating table if we provide the country with military support," the official said.
"The best way to support peace is to support Ukraine."
According to him, this will help Ukrainians to defend themselves against aggression.
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The secretary general acknowledged that aid to Ukraine is reflected in rising food and electricity bills, which means hard times for many households in Europe.
He also noted that it is necessary to remember that "the people of Ukraine pay with their blood every day."
Stoltenberg also emphasized that Putin's victory in the war would mark the beginning of an era when other despots would use violence to achieve their goals.
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"It could mean more war and more suffering," he stressed.
"It would make our world even more dangerous. It is in our own interests that Ukraine wins."