The issue of women forced into sexual slavery for Japanese troops during World War II is a hugely emotional subject that has marred ties between the South and its former colonial ruler, Japan.
Moon’s comments came a day after Seoul’s foreign ministry said the deal — which was pushed and endorsed by his predecessor Park Geun-Hye — was faulty and had “failed to reflect the victims’ views”.
The unpopular agreement was meant to end the decades-long dispute with a Japanese apology and a payment of 1 billion yen ($8.8 million) to survivors.
But it sparked anger among some survivors seeking an explicit apology from the Japanese government for the wartime abuses.
Following Moon’s decision to order a review of the deal after being elected to office this year, a task force published a report Wednesday saying the agreement was rushed and did not do enough to seek out the opinions of the victims, often known by the euphemism “comfort women”.
“It has been confirmed that the 2015 deal … was seriously flawed,” Moon said in a statement released on Thursday.
“Although the 2015 deal was an official agreement endorsed by the leaders of both countries, I’d like to make it clear that the deal cannot solve this issue of ‘comfort women’.”
The latest revelation by the task force is “regrettable but unavoidable,” Moon added, telling officials to “come up with follow-up measures at the earliest date” without elaborating further.
It is unclear whether Seoul will call for renegotiation with Tokyo or walk away from the deal.
Japan has urged South Korea to stick with the 2015 agreement, saying any attempt by Seoul to revise the original deal “cannot be acceptable whatsoever” and would leave bilateral ties “unmanageable”.
The row comes as both countries face shared nuclear and missile threats from North Korea, whose recent military standoff with the US sparked fears of war on the Korean peninsula.
Attempts to reopen the agreement may also dent the South’s credibility in the diplomatic community, Seoul’s top-selling Chosun daily said in an editorial on Thursday.
“The ‘comfort women’ issue is important. But if we demand renegotiation over the deal made two years ago, bilateral ties will be shattered,” it said.
“We can’t let ourselves trapped in the past at a time like this when North Korea’s nuclear threat is growing rapidly.”
Mainstream historians say as many as 200,000 women — mostly from Korea but also other parts of Asia including China — were forced to become sex slaves for Japanese soldiers during the war.
The Japanese government denies it is directly responsible, insisting that “comfort women” were recruited by civilians and that the army brothels were commercially operated.
Despite the 2015 agreement, ties between the two neighbours remain tense over statues placed outside Japanese diplomatic missions by South Korean activists in memory of the victims.