SEOUL, June 20 (Xinhua) -- South Korean President Moon Jae-in said Wednesday that an action plan by the Democratic People's Republic of Korea (DPRK) and reciprocal measures by the United States will be needed to denuclearize the Korean Peninsula.

Moon made the remark during an interview with Russian media ahead of his state visit Thursday to Moscow for a summit meeting with Russian President Vladimir Putin, according to the presidential Blue House of South Korea.

He said the DPRK needs to offer a concrete action plan for denuclearization, while the United States needs to offer comprehensive reciprocal measures to it, to eventually implement their respective proposals.

The South Korean leader said the DPRK-U.S. summit was a "great success" that was greater than he had expected, and Pyongyang and Washington had made a grand historical achievement.

Top DPRK leader Kim Jong Un and U.S. President Donald Trump met in Singapore on June 12 for the first DPRK-U.S. summit, agreeing to complete denuclearization in return for security guarantees for the DPRK.

The remaining task to do, Moon said, would be a complete, rapid implementation of the Kim-Trump agreement.

Pyongyang has stopped its nuclear and missile tests, dismantling its main nuclear test site in which the country carried out all of its six nuclear detonations.

In return, Washington and Seoul decided to suspend their summertime war game, codenamed Ulchi Freedom Guardian, a computer-simulated command post exercise slated for August.

Moon said the DPRK leader's denuclearization commitment was clear as he was willing to develop the economy by "putting down" its nuclear program if Pyongyang can get security guarantees in return for denuclearization.

The leaders of the two Koreas held their first summit on April 27 at the inter-Korean border village of Panmunjom, agreeing to complete denuclearization and enhance inter-Korean relations.

Moon said he and Putin had a shared goal of the complete denuclearization and a peace regime settlement on the Korean Peninsula, noting that when inter-Korean cooperation is resumed after the peace settlement, the two Koreas and Russia should increase trilateral economic cooperation.

The trilateral economic cooperation, Moon said, can start in the railway, natural gas and electricity sectors as those can be launched quickly and can provide economic benefits to the three countries.