South Korea’s spy agency said North Korea appears to have sent additional troops to Russia to assist its war against Ukraine. 

The National Intelligence Service(NIS) said Thursday that after a monthlong lull, North Korean troops have been back on the front lines in the Kursk region since the first week of February. 

The NIS added that additional troops appear to have been deployed, but said the agency is still working to determine exactly how many. 

It marks the North’s second dispatch of troops, after it sent about eleven-thousand soldiers to the Kursk region in October last year. 

A military official in Seoul said North Korea appears to have sent more than one-thousand troops this time.