NATO and Türkiye believe that it is crucial to support Ukraine to end the war of aggression being conducted by Russia, NATO Secretary-General Jens Stoltenberg said Saturday.

Stoltenberg, who arrived in Türkiye on a three-day visit on Thursday, praised Ankara's role during the ongoing conflict.

Speaking to Anadolu Agency (AA) on Saturday, a day after meeting President Recep Tayyip Erdoğan in Istanbul, he said: "I commended Erdoğan and Türkiye for what they have done, both in providing support to Ukraine, but also in facilitating the deal enabling the export of grain from Ukraine."

"This is important for the whole world, especially the poor world, and it helps reduce food prices. Türkiye has played a key role in making that possible," he said.

Stoltenberg reiterated that the Ukraine conflict is a "war of choice."

"This is Russia, President Vladimir Putin invading another country ... We have to understand that President Putin started this war. This is a war of choice, and he can end this war tomorrow," he said.

Emphasizing Ukraine's "right to defend themselves" and reclaim its territory, Stoltenberg said: "If President Putin and Russia stop fighting, then we'll have peace. If President Volodymyr Zelenskyy and Ukraine stop fighting, then Ukraine will cease to exist as an independent and sovereign nation."

He said the international community has the "responsibility to support Ukraine to enable them to defend themselves."

"Of course, I believe that I hope that this war also at some stage will end at the negotiating table. But we also know that what Ukraine can achieve around that table in negotiations is absolutely dependent on the strength on the battlefield," he added.

"So if we want Ukraine to prevail as a sovereign independent nation, then we need to provide military support to Ukraine to strengthen their hand and to maximize the likelihood for an outcome in all negotiations which is acceptable for Ukraine."

Stoltenberg also criticized Russia's "reckless" and "dangerous nuclear rhetoric."

"Russia must understand that nuclear war cannot be won and ... will have severe consequences for Russia," he stressed.

"The probability for any use of nuclear weapons in Ukraine remains low, but at the same time, the consequences are so big and so devastating. So we need to take the risk seriously," said the NATO chief.

Stoltenberg's Türkiye visit came after Russia announced last week that it was pulling out of the grain deal, accusing Ukraine of attacking its Black Sea fleet with drones.

However, Türkiye and Russia announced Moscow's return to the deal's implementation on Wednesday, following mediation from Ankara and the United Nations.

Türkiye, the U.N., Russia and Ukraine signed the agreement on July 22 in Istanbul to resume Black Sea grain exports, which were paused after the war began in February. A Joint Coordination Center with officials from the three countries and the U.N. was set up in Istanbul to oversee the shipments.