U.S. House Speaker Nancy Pelosi says she is not "optimistic" about the upcoming U.S.-North Korea summit in Vietnam but "hopeful" the meeting will help establish peace on the Korean Peninsula.

A visiting South Korean parliamentary delegation met with Pelosi in Washington Tuesday and said the House speaker pointed out that the first U.S.-North Korea summit in Singapore last year generated no result, adding there needs to be evidence of Pyongyang's commitment.

Pelosi also raised the issue of Korean victims of Japan's wartime sexual slavery, saying she understands the victims' rights were violated and would like to see Tokyo respect its agreements with Seoul.

The delegation also met with House Minority Leader Kevin McCarthy as well as the chairman of the House Foreign Affairs Committee, Eliot Engel, and highlighted the South Korea-U.S. alliance in the denuclearization process.