"We have to exhaust every other remedy," Pelosi said.
Pelosi's comments came after the Pentagon sent a letter
to lawmakers late last month saying the only way to destroy all of North Korea's nuclear weapons "with complete certainty" would be to conduct a ground invasion of the country.
Pelosi said she was worried not only about the threat of North Korea conducting a strike, but also about Pyongyang selling nuclear technology to third parties.
"My concern about North Korea is not only what they're doing, but what they're advertising," Pelosi said. "They may want to sell some of this technology."
The California Democrat said President Donald Trump's current trip to Asia presents an important opportunity for the US to get the international community, including Russia, cooperating on diplomacy with North Korea.
Pelosi referenced Trump's recent remark
that he is "the only one that matters" when asked in an interview about vacant positions in the State Department, adding that the President must go into his talks with as much information as possible.
Russia has a "mixed agenda" on North Korea, she warned, adding, "I hope the President goes into the meeting really informed."
The Pentagon's letter said it fully supported the diplomatic efforts, including economic sanctions, to pressure North Korea, and said the Joint Chiefs of Staff had not seen a change in North Korea's offensive posture.
In a separate interview on the same program, California Democratic Sen. Dianne Feinstein said the Pentagon letter "is the most bleak assessment," and that she had spoken about the situation with Defense Secretary James Mattis.
"The worst alternative is a war which could become nuclear," Feinstein said.
She stressed the importance of Secretary of State Rex Tillerson's diplomatic efforts, saying a war with North Korea would be guaranteed to kill hundreds of thousands of people.