Prime Minister Han Duck-soo (left) is seen arriving to his office in Seoul on Friday. (Yonhap)

With incumbent President Yoon Suk Yeol to be suspended following the National Assembly's approval to put him in front of the Constitutional Court for trial, Prime Minister Han Duck-soo will serve as acting president for up to six months.

Han has become South Korea's first acting president in eight years, after Hwang Kyo-ahn, the former prime minister who assumed former President Park Geun-hye's role in December 2016.

Under Article 71 of the South Korean Constitution, if the president is deemed unable to perform duties for any reason, the prime minister shall assume the powers and duties of the incumbent president.

Han's role as acting president will start as soon as an authentic copy of the impeachment resolution is delivered to Yoon. Previous cases in South Korea's modern history have indicated that this process takes at least three hours.

In theory, Han will be entrusted with Yoon's power -- namely, to serve as commander in chief of the South Korean armed forces, represent the international persona of the state, issue executive orders in case of calamity or crisis, appoint and dismiss public officials and grant amnesty, among other powers.

History shows that an acting president is also able to exercise the presidential power to veto bills.

Goh Kun, the former prime minister who served as acting president in 2004 in lieu of the late former President Roh Moo-hyun, vetoed bills including a revision to the Amnesty Act, which was meant to allow the National Assembly to express its opinion should special amnesty be granted. Roh was the first South Korean president to have stood before an impeachment trial at the Constitutional Court, but was reinstated after two months.

Awaiting the acting president are six bills that the ruling People Power Party's Floor Leader Rep. Kweon Seong-dong said Friday he would ask the administration to send back to the parliament for a revote.

Among them are a revision of the Grain Management Act, as well as separate special counsel probe bills targeting Yoon for insurrection and Yoon's wife Kim Keon Hee for corruption.

Prime Minister Han Duck-soo (right) is seen talking with Deputy Prime Minister Choi Sang-mok in the main chamber of the National Assembly on Friday. (Yonhap)

But uncertainties abound over whether Prime Minister Han might exercise his executive power, given that police have also accused Han of involvement in the insurrection case in the wake of Yoon's martial law declaration on Dec. 3. The main opposition Democratic Party of Korea, which holds a majority of seats at the parliament, is also mulling Han's impeachment, but the move has been met with mixed views within the party.

Should Han be suspended as well, his replacement would assume Han's power in accordance with the presidential line of succession.

Under Article 26 of the Government Organization Act, Deputy Prime Minister and Minister of Economy and Finance Choi Sang-mok is ahead of other members of the Cabinet in order of priority. Deputy Prime Minister and Minister of Education Lee Ju-ho is behind Choi. Lee is followed by Science and ICT Minister Yoo Sang-im, Foreign Affairs Minister Cho Tae-yul and Unification Minister Kim Yung-ho, among others.

According to the Presidential Security Service, a new group of presidential bodyguards will work for Han and his wife pursuant to its standard for the incumbent president. It will also discuss concrete details of the security service with Han's office.

The PSS noted that presidential security for Yoon will be maintained as is, despite being suspended from his position.