Boris Johnson is planning another trip to Kyiv to meet Ukrainian President Zelenskyy

Boris Johnson is planning a trip to Kyiv to visit the Ukrainian president as Russia made its first breakthrough on the battlefield in months.

The former prime minister is a hugely popular figure in the war-torn country, having visited Ukraine three times since the conflict began.

Mr Johnson has established a connection with Volodymyr Zelensky during frequent phone calls at the office and they are said to consider each other “friends”. He has told allies he intends to return to Kyiv in the coming months to show his public support, The Guardian reported.

No10 are said to have been unaware of Mr Johnson’s plans and a spokesman for Rishi Sunak declined to comment yesterday. But an ally of the Prime Minister suggested Mr Johnson was trying to have his “Churchill moment”.

Boris Johnson plans a trip to Kyiv to visit Ukrainian President Zelenskyy for the fourth time (pictured together in August)

They said: “This is both about how Boris sees his role on the world stage and about supporting Ukraine.

“The situation there remains extremely fragile, so he must be careful not to jeopardize Rishi’s relationship with Zelensky.”

A source close to Mr Johnson declined to comment last night amid speculation he could become special envoy for Ukraine. It came as Russia yesterday claimed its forces had captured the town of Soledar in eastern Ukraine in what would be its first victory in six months.

Ukraine denied the Russians were in control and said “serious fighting” was ongoing in the main salt-mining town. However, there were reports of Ukrainian forces retreating in what appeared to be a controlled retreat.

Russia’s Defense Ministry said it had “completed” the “liberation” of Soledar and that the victory would pave the way for more “successful offensive operations” in the Donetsk region. The country claimed that Soledar’s capture “allowed to cut off the supply routes of Ukrainian troops” and encircle them.

A source close to Mr Johnson declined to comment last night amid speculation he could become special envoy for Ukraine

But the US Institute for the Study of War called the move a “small victory” that was “overkill.”

Moscow’s last major successes came in June and July with the capture of Lysychansk and Severodonetsk in the eastern Luhansk region. Putin’s forces have since suffered a series of heavy defeats, including the withdrawal from the southern city of Kherson.

The battle for Soledar is taking place in Moscow after a major reorganization, with Chief of Staff Valery Gerasimov now in charge of operations in Ukraine. A Moscow-based analyst, who spoke on condition of anonymity, said the move was “unprecedented” and pointed to “very serious problems” for Russia on the battlefield.

Meanwhile, Ukraine’s Defense Minister Oleksiy Reznikov said the country has effectively become a NATO member, even though the alliance is reluctant to enter a conflict with Russia.

Mr Reznikov said he was confident Western allies would shed their hesitation in supplying Ukraine with heavier weapons such as tanks and fighter jets.

“This concern about the next level of escalation is a kind of protocol for me,” he told the BBC, dismissing NATO fears of provoking Russia.