Markey is the ranking member of the Senate Subcommittee on East Asia and Pacific Affairs.

Heightened tensions with North Korea are expected to top their discussions.

"The US delegation may ask about our reconciliation policy toward North Korea and the president will explain the principles our government has on this," the presidential aide said on the customary condition of anonymity.

Moon could also reiterate his stance that no military action can take place on the Korean Peninsula without South Korea's consent. Moon has repeatedly made the remark in recent weeks in an apparent effort to calm tensions down in the wake of an exchange of belligerent rhetoric between Washington and Pyongyang.

Also attending the meeting will be Nam Gwan-pyo, a deputy national security adviser to Moon.

Moon is also scheduled to meet later in the day with Japanese lawmakers belonging to the Japan-Korea Parliamentarians' Union, including its Japanese chair, Fukushiro Nukaga.

Moon is expected to use the meeting to call for closer cooperation between Seoul and Tokyo in coping with North Korean provocations.

The two sides could also talk about how to improve relations between the two countries that have long been frayed over historical issues, including Japan's mobilization of Korean women as sex slaves for its troops during World War II. (Yonhap)