The issue of expenses concerning the advanced anti-missile system currently being installed here is not subject to renegotiations, said acting President and Prime Minister Hwang Kyo-ahn on Thursday, in his last press briefing as acting president.

He also said he plans to offer his resignation as prime minister as soon as possible once the incoming administration kicks off next week.

“With the presidential election due in five days, our top priority is to administer the election in a fair manner and to make sure that no vacuum occurs in state affairs,” Hwang told reporters during a luncheon briefing held at the Prime Minister’s Office in Samcheong-dong, Seoul.

As prime minister, Hwang has been filling in the presidential post since December, when then-President Park Geun-hye was suspended from power upon the legislature’s passage of a bill on her impeachment.

His temporary presidential function will hold effect until Wednesday, the day after the May 9 election, when the new president-elect is to take office.

Wrapping up his turbulent five months as acting president, Hwang elucidated on a number of disputed issues, such as the deployment of the Terminal High Altitude Area Defense or his connection to the ousted Park administration.

“THAAD is not a toy but a military defense system, so details of its deployment need not be revealed in advance for security reasons,” he said.

“A number of Patriot missiles, which are the preliminary stage to THAAD, are currently installed here, but none of the details had been revealed in advance.”

Hwang also reiterated the government’s stance that the THAAD-related expenses had already been stated in the Korea-US mutual defense treaty and need not be renegotiated, contrary to US President Donald Trump’s recent remarks that South Korea should bear the financial burden.

“The expenses should be covered by the country which actually operates the weapon, the US in this case, as stated in the mutual treaty,” he said.

“The US is also aware that renegotiation is not plausible at the current stage when the (THAAD) deployment hasn’t even been completed yet.”

The prime minister also alluded to stepping down from his post as soon as the incoming president takes power.

“Once the presidential election is over, I will resign (from the prime ministerial post),” Hwang said.

“But as the incoming government is to kick off without the usual preparatory period, there may be a considerable vacuum in state powers, and if the president-elect has (a different) opinion, I will comply.”

But he added that the best scenario would be for him to step down and give way to new powers.

As for the recent dispute over the designation of Cheong Wa Dae documents -- including Park’s unaccounted for seven hours on the day of the Sewol ferry sinking in 2014 -- for historical preservation, Hwang explained his action was to abide by the law.

“It is stated by law that presidential documents should be handed over to the National Archive before the end of the term,” he said.

“But I understand that under the current circumstances, many suspect that the intention was to conceal (the truth).”

In such cases, it is possible to access the archived documents either by two-thirds consent at the National Assembly or through a court petition, he explained.

“I only acted upon the law. Why would I possibly want to conceal evidence?” Hwang said.

By Bae Hyun-jung (tellme@heraldcorp.com)