Putin 'plans to deploy thousands of North Korean soldiers to dig tunnels beneath the front lines, and attack Ukraine from the rear'

North Korea is believed to be sending thousands of tunnelling troops to Russia to open a new 'underground front' on the border with Ukraine as part of a deal with Vladimir Putin.

Kyiv suspects that military engineers being sent by Kim Jong Un are not for 'restoration work' in the Donbas, as stated, but for an ulterior purpose.

Russia has already used tunnels twice in the conflict, in Avdiivka and Toretsk, says United Ukraine analyst Aleksey Kushch, who has warned of a Putin bid to break the war 'deadlock' by digging tunnels in summer and autumn.

'Judging by various sources, approximately five engineering brigades of the North Korean army may arrive in Donbas,' he said.

If so, this could be 15,000 men, or more. Kushch said it was 'illogical' that they are working on 'restoration' while the war is 'in full swing'.

Kim Jong Un meets soldiers during a visit to a western operational training base in North Korea

Kim Jong Un, right, and Russia's President Vladimir Putin shake hands after signing a comprehensive strategic partnership in Pyongyang, North Korea Wednesday, June 19, 2024

He said: 'The Russian breakthrough near Avdiivka and Toretsk occurred, among other things, as a result of the use of underground tunnels.'

In Avdiivka, a tunnel already existed, while in Toretsk it was dug - almost two miles long.

This was 'a new technology of war… to protect against attacks from drones and artillery - undermining, going to the rear, seizing positions, digging in', he said.

He warned: 'Who can dig better than the Koreans?'

Pyongyang has 'developed its own theory of underground warfare' based on its operations in the Korean War.

Tunnels stretching between North and South Korea, which defectors said Kim Il Sung had ordered his army to build, were discovered during the 1970s.

Korea's underground warfare techniques have reputedly been developed amid paranoia over a Western attack with nuclear weapons. 

In eastern Ukraine 'underground tactics can be used for a 'creeping offensive' and breaking through complex, layered defences, and to minimise losses from drone and artillery strikes', he said.

A tank T-64 drives by in Novoselivka Persha after driving out of Avdiivka, Ukraine

'I would not be surprised if the 'underground war' strategy was approved during Putin's visit to the DPRK. Perhaps it was suggested by the North Koreans themselves.'

Ukraine needed 'to technically prepare for such risks', he added.

In Avdiivka, Russian commander Anton 'Zima' Morozov, 28, led troops on all fours down a one and a quarter mile concrete pipe - which the Russians had spent months clearing.

They got behind Ukrainian positions during one of the bloodiest and closely fought battles of the war.

A Russian account of this operation said: 'When everything was ready, over 100 of our attack soldiers made their way through the pipe to the rear of the Ukrainian key position called Tsar's Hunt [formerly a hotel and recreation complex].

A Ukrainian servicemen is seen during a training in the Donetsk region, Ukraine, on Saturday, June 29, 2024

'Most of the defending Ukrainian Armed Forces were destroyed, and about a dozen were captured.

The operation gave the Russians a key bridgehead, hastening a Ukrainian retreat from Avdiivka.

Morozov was recommended for the Kremlin's highest honour - Hero of Russia - but was assassinated before he could receive it.

He was shot 11 times in an apparent Ukrainian operation.