Choo Mi-ae, the leader of the ruling Democratic Party, embarked on a six-day visit to the United States on Tuesday for talks with US officials, lawmakers and scholars over the bilateral alliance, North Korean threats and trade, her aide said.

Choo's trip comes as Seoul and Washington strive to rein in a provocative Pyongyang and amend their free trade agreement (FTA), which US President Donald Trump called "quite unsuccessful and not very good for the US" during his visit to Seoul last week.

Before departing, Choo said that the purpose of her trip is to foster a broad consensus with Washington over Seoul's push for a peaceful resolution to the nuclear standoff and help set the tone for "smooth" FTA renegotiations.

"Through talks with US politicians, White House officials and business leaders, I would like to reaffirm the solid South Korea-US security alliance," Choo told reporters.

"I will also deliver Seoul's position on the FTA and foster the mood for cooperation in enhancing bilateral (economic) interests," she added.

Upon arrival in Washington D.C. on Tuesday (US time), Choo will first visit the Korean War Veterans Memorial to pay respects to those who fought under the U.N. banner to defend South Korea during the 1950-53 war.

Choo will then meet White House chief economic director Gary Cohn to discuss the FTA. Washington has been seeking to revise the five-year-old agreement, blaming it for America's growing deficit in goods trade with Korea despite its surplus in services trade.

Choo was also set to meet House Speaker Paul Ryan to discuss pending issues between the two countries and ways to bolster exchanges between their legislatures.

Her schedule includes meetings with top US lawmakers such as House Minority Leader Democrat Nancy Pelosi, Senator Ben Cardin of the Senate Foreign Relations Committee, and Cory Gardner, the chairman of the Senate Foreign Relations Subcommittee on East Asia.

Her aides have been seeking to arrange talks with top White House officials such as deputy national security advisor Rick Waddle.

After her visit to the US, she plans to travel to Beijing on Nov. 30 for a four-day visit. It was arranged on the invitation of the International Liaison Department of the Communist Party of China (CPC).

Choo will attend a gathering of the world's political party leaders that will be hosted by the CPC under the main theme of "the responsibility of political parties to establish a community sharing a common destiny and a beautiful world," her aide said.

Her party is seeking to arrange a meeting between Choo and Chinese leader Xi Jinping, her aide added.

Choo also plans to visit Russia next month and Japan early next year. (Yonhap)