"We need to provide support to Ukraine now, including military support, because that's the only way to convince Russia that they have to sit down and negotiate in good faith and respect Ukraine as a sovereign independent nation in Europe," the NATO chief said, as quoted by the BBC.
"What we do know is that what Ukraine can achieve around that table is totally dependent on the strength on the battlefield," he added.
In another recent interview, Stoltenberg urged allies to supply more weapons to Ukraine to help it defend itself against Russian attacks.
"I call on allies to do more," Stoltenberg said in an interview published last week by German news agency DPA.
He added that it was especially important that Ukraine receive new supplies of ammunition and spare parts for military equipment.