South Korea’s Defense Ministry said Tuesday that it’s pushing to end most of the existing military service exemptions for men by 2023 to cope with an expected shortage in manpower.

The plan to phase out the exemptions beginning in 2020 would require support from other ministries and state agencies to be carried out, said a Defense Ministry official, who didn’t want to be named, citing office rules.

South Korea requires able-bodied men to finish two years of military service to maintain a strong force in face of threats from rival North Korea.

But according to the Defense Ministry, 28,000 men have been excused from active military duty this year through exemption programs, including service with the country’s police and firefighting forces. Engineering and science majors can also opt to temporarily work at small industrial firms and research organizations instead of serving in the military.