U.S. National Security Advisor Jake Sullivan believes that Ukraine will have to solve the problem of the lack of human resources in the Armed Forces by lowering the conscription age, Sullivan said on Monday in an interview with Bloomberg.

Sullivan said Ukraine has already lowered the conscription age from 27 to 25. In his opinion, the issue of replenishing manpower in the Armed Forces of Ukraine has "evolved" since then.

"This issue [the manpower issue] has become more acute over the course of the past year. And the need of Ukraine to be able to fully populate its brigades and battalions, as we have flooded them a massive quantity of ammunitions and military equipment, they need," he said.

Sullivan said this problem was discussed with the "Ukrainian team." "That is a sovereign decision that Ukraine is going to have to make, but we have been crystal clear, including publicly, that manpower issue is an acute concern and it is something that Ukraine will have to address, even as we do our part to get them the ammunition they need," he said.