SEOUL, South Korea (AFP) -- More than 1,000 North Korean soldiers have been killed or wounded in Russia’s war with Ukraine, South Korea’s Joint Chiefs of Staff (JCS) said on Monday.

The new figure follows a report by Seoul’s spy agency to members of parliament last week, which said at least 100 North Korean soldiers had been killed since entering combat in December.

Pyongyang has sent thousands of troops to reinforce the Russian military, including to the Kursk border region, where Ukrainian forces seized territory earlier this year.

“Through various sources of information and intelligence, we assess that North Korean troops who have recently engaged in combat with Ukrainian forces have suffered around 1,100 casualties,” the JCS said in a statement.

“We are particularly interested in the possibility of additional deployments” of North Korean soldiers to aid Russia’s war effort, the JCS added.

Pyongyang is reportedly “preparing for the rotation or additional deployment of soldiers,” the JCS said.

Intelligence also suggests that the nuclear-armed North is “producing and providing self-destructible drones” to Russia to further assist Moscow in its fight against Ukraine, it added.

The North was also supplying “240mm rocket launchers and 170mm self-propelled artillery” for the Russian army, the JCS said.

Seoul’s military noted that North Korea was aiming to modernize its conventional warfare capabilities based on combat experience in the Russia-Ukraine war.

“This could lead to an increase in the North’s military threat toward us,” it said.

The latest findings align with a report by the National Intelligence Service, which informed lawmakers that “Russia might offer reciprocal benefits” for North Korea’s military contributions, including “modernizing North Korea’s conventional weaponry.”

‘More destruction’

Meanwhile, Russian President Vladimir Putin on Sunday vowed to bring more “destruction” to Ukraine in retaliation for a drone attack on the central Russian city of Kazan a day earlier.

Russia accused Ukraine of a “massive” drone attack that hit a luxury apartment block in the city, some 1,000 kilometers from the frontier.

Videos on Russian social media networks showed drones hitting a high-rise glass building and setting off fireballs, though there were no reported casualties as a result of the strike.

“Whoever, and however much they try to destroy, they will face many times more destruction themselves and will regret what they are trying to do in our country,” Putin said during a televised government meeting on Sunday.

Putin was addressing the local leader of Tatarstan, the region where Kazan is located, in a road-opening ceremony via video link.

The strike on Kazan was the latest in a series of escalating aerial attacks in the nearly three-year conflict.

Ukraine has not commented on the strike.

Putin has previously threatened to target the center of Kyiv with a hypersonic ballistic missile in response to Ukrainian attacks on Russian territory.

And the defense ministry has called Russian strikes on Ukrainian energy facilities over recent weeks retaliatory hits for Kyiv using Western-supplied missiles to hit Russian air bases and arms factories.