A "small number" of North Korean troops have already been deployed in Russia's Kursk region on the Ukrainian border, the Pentagon said on Tuesday, expressing concern that they will be used in combat against Kyiv's troops.

Pentagon spokesperson Major General Pat Ryder said there are "indications that there's already a small number that are actually in the Kursk Oblast, with a couple thousand more that are either almost there or due to arrive imminently".

"We are concerned that they do intend to employ these forces in combat against the Ukrainians, or at least support combat operations against the Ukrainians in the Kursk region," Major General Ryder said, adding that it remains to be seen exactly how they will be used.

NATO chief Mark Rutte said the previous day that North Korean forces were in Kursk, while the United States had until now only expressed concern that they could be deployed there.

 A total of around 10,000 North Korean troops are currently in Russia, a spokesperson for the Pentagon said in a statement earlier this week.

Russia and North Korea to hold talks

North Korean Foreign Minister Choe Son Hui will hold strategic consultations in Moscow with her Russian counterpart Sergei Lavrov, Russia's Foreign Ministry announced on Wednesday.

"In accordance with the agreement reached during the Russian-Korean summit meeting in Pyongyang in June, the Minister of Foreign Affairs of the Democratic People's Republic of Korea, Choe Son Hui, is arriving in Moscow on an official visit to hold strategic consultations with Russian Foreign Minister Sergei Lavrov," ministry spokesperson Maria Zakharova said.

"This is normal diplomacy. This should not raise questions for anyone," she said.

The meeting will mark the North Korean foreign minister's second visit to Russia in six weeks.

The Kremlin has said Russian President Vladimir Putin has no plans to meet her.

Russia and North Korea have boosted their political and military alliance in the course of the Ukraine conflict.

Both are under sanctions -- Pyongyang for its nuclear weapons program, and Moscow for its war against Kyiv.

When asked if Russia would withdraw from the UN sanctions, Ms Zakharova said the situation was developing and Moscow was "drawing conclusions".

She said the sanctions had failed to resolve tensions on the Korean peninsula and had been turned into a "blunt weapon" against Pyongyang by the United States and its allies.

Russian Deputy Foreign Minister Andrei Rudenko held talks with China's Foreign Minister Wang Yi on Wednesday to discuss the war in Ukraine, reaffirming their relations were unchanged by "the international situation".

Kyiv renews push to recruit troops

Kyiv announced a fresh mobilisation drive for their defence forces on Tuesday.

The Secretary of Ukraine's National Security Council Oleksandr Lytvynenko told parliament that the army planned to recruit another 160,000 people.

Ukrainian President Volodymyr Zelenskyy suggested in a video released on Wednesday, that Kyiv has requested supplies of long-range US Tomahawk missiles, as he made critical remarks about "confidential" information he said had been leaked.

During his remarks, he referred to the "victory plan" he pitched to US President Joe Biden — which he has said could pressure Moscow to negotiate an end to the war in good faith.

"When a lot of countries began to support the victory plan, you see what's going on now in media – they said that Ukraine wanted a lot of missiles, like Tomahawks," he said.

"But it was confidential information – between Ukraine and the White House. How to understand these messages?"

"So it means between partners – there's no any confidential things."

The New York Times cited a senior US official on Tuesday as saying Mr Zelenskyy had asked for Tomahawk missiles, something the official said was totally unfeasible.

Mr Zelenskyy told Nordic journalists that Ukraine has received only 10 per cent of the US military aid approved by Congress earlier this year.

"You do your job. You count on reserves, you count on special brigades, you count on such equipment. And if you get 10 per cent of all the package [that] has already been voted on … it's not funny," he said.

Mr Zelenskyy added that the slow pace of weapons supplies was not a question of funding.

"Its always the question of bureaucracy or logistics, ideas or scepticism … This we will give you, this — [we] will not," he said.

He also said NATO countries had pledged to supply Ukraine with six or seven air defence systems, which Ukraine increasingly relies on to repel long-range Russian strikes, by the beginning of September but that Kyiv had not yet received all of them.

Ukrainian troops have been conducting a ground offensive in Kursk since August and control several hundred square kilometres of Russian territory.

Meanwhile, Moscow said on Tuesday it has wrested control of Selydove, Bogoyavlenka, Girnyk and Katerynivka in the Donetsk region — the latest advances on their march toward the industrial hub of Pokrovsk.

A South Korean presidential official told Reuters on Wednesday they were considering sending military monitors to Ukraine to observe the North Korean troops there.

ABC/wires