He warned that a Ukrainian defeat in the war would further degrade global security, and urged the international community to continue supporting Kyiv.
Read also: Ukraine needs 'significantly' more weapons to prevail, NATO's Stoltenberg says
"President Putin can end the war today," NATO website quotes Stoltenberg's speech.
"But the challenge is that we don't see any signs that President Putin and rules in Moscow are preparing for peace. We see the opposite. We see that they are preparing for more war, that they are mobilizing more soldiers, more than 200,000, and potentially even more than that."
According to the secretary, Russia is actively procuring weapons from authoritarian regimes in North Korea and Iran.
Read also: NATO's Stoltenberg urges more advanced weapons for Ukraine
"And most of all, we have seen no sign that President Putin has changed his overall goal of this invasion that is to control a neighbor, to control Ukraine," said Stoltenberg.
He added that should Putin win the war, authoritarian leaders across the globe will be emboldened to attempt to achieve their goals by use of force.
Read also: Russians plan offensive actions for February, says analyst
"And that will make the world more dangerous and us more vulnerable, so therefore it is so important that we continue to support Ukraine," he concluded.
Ukrainian military leadership have previously warned that Moscow is gearing for another major offensive in February-March 2023.