Reducing the military service period to 18 months from the current 21 months was one of Park's key campaign pledges. Conservative critics have warned that such a reduction could leave the armed forces without enough troops at times of high tension with North Korea.
During the briefing, the ministry said the issue should be reviewed "carefully," sources said.
Military officials say the proposed reduction would leave the armed forces short by an average 27,000 troops a year until 2030, and hiring noncommissioned officers to make up for the shortfall would cost the nation 700 billion won (US$662 million) a year.
By law, all able-bodied South Korean men should fulfill military service.
The ministry and the transition team had no differences on other issues, such as Seoul's planned retaking of wartime operation control over its troops from the United States in 2015. On Park's election promise to raise wages of soldiers, the ministry came up with a plan to give a 20 percent raise every year until 2017, sources said.
Changing the military command structure is also considered a central issue as the transition team's defense policy chief, Kim Jang-soo, opposes the ongoing revision to empower each chief of the Army, the Navy and the Air Force to exercise both administrative and operation controls.
Currently, operational control of the military lies with the Joint Chiefs of Staff chairman.
It was unclear how the ministry reported to the committee on the issue.
The defense ministry was the first of the 46 ministries and other government offices and committees to report to the transition team on their existing and future policies, a schedule that officials say underlines the importance the next government puts on national security and safety of the people.
Other offices that offered briefings on the first day include the Small and Medium Business Administration and the health and welfare ministry. Both are considered higher-priority offices as Park has repeatedly said she would take greater care of smaller businesses and expand welfare programs.
The weeklong briefings will run through Thursday next week.
The small business administration reported that it should be upgraded to an independent minister-level agency to carry out Park's campaign promises more effectively. Currently, the agency is under the knowledge economy ministry that handles industrial and energy affairs, according to sources.
The agency also briefed the committee on policy plans to protect smaller firms and tighten the reins on conglomerates, such as designating specific areas where only small companies can operate, and expanding punitive measures for big businesses that abuse smaller subcontractors.
Committee officials said the primary focus of the policy briefings will be on charting policy road maps in line with Park's instruction that the team should focus on fleshing out her campaign pledges into specific policies, rather than trying to make brand new policy proposals.
Main points the team will look into during briefings include whether the reports are appropriate to realize Park's philosophy on state affairs, whether the presented policies are workable and how to cut costs and secure funds to carry out major policies.