A high-ranking Ukrainian official says the next few months will be pivotal for his troops on the battlefield. He tells NHK that an extended conflict could favor the Russian forces.

Andriy Yermak is the head of Ukraine's presidential office. In an interview with NHK, he said, "If the fighting in this war lasts until winter, it will become more and more difficult to regain territory. We are focusing our discussions on taking all possible measures to break the deadlock before that time comes around."

Yermak said Ukrainian troops have been intensifying counterattacks in the south. He added that their goal is to win back 100 percent of the territory seized by Russia.

Yermak said, "In this war, we will never make concessions in terms of our independence, territorial integrity, and sovereignty."

Yermak called on the US and Western allies to impose further sanctions against Russia. He said leaders in Moscow continue to use energy exports as leverage to lift the sanctions.

British defense officials say the Russians are making only slow progress in the east. They say commanders are likely reallocating a significant number of forces from the northern Donbas region to the south.

Also in the south, the first ship carrying grains since the start of the Russian blockade left from the port of Odesa on Monday. It is due to arrive off the coast of Istanbul for inspection.

However, Russian forces in the southern region continue their attacks. That raises doubts about whether further grain shipments can continue smoothly under a deal brokered by the UN and Turkey.