South Korea's President Park Geun-hye told Congress on Wednesday that she will never accept a nuclear-armed North Korea and that provocative actions by the reclusive communist country "will be met decisively."
But Park also said South Korea was ready to provide humanitarian aid, without linking it to the political situation on the divided Korean Peninsula, and will try to build trust so long as the North's authoritarian government responds in kind.
Park is on her first overseas strip since taking power in February, two weeks after the North conducted its latest nuclear test, the third since 2006, and increased tensions in the region.
On Tuesday, Park and President Barack Obama delivered a strong message of solidarity in the face of threats from North Korea.
U.S. lawmakers gave Park a prolonged ovation as she entered the House to address a joint meeting of Congress, evidence of the tight bond with the U.S. forged during the Korean War.
Her speech started with a tribute to U.S. veterans of the 1950-53 conflict, a group that included four congressmen.
Park's visit marked the 60th anniversary of the military alliance with the U.S. that maintains 28,500 troops in South Korea.
Park said she is "president of a grateful nation," and that backed by the might of the U.S.-South Korean alliance, "no North Korean provocation can succeed."
South Korea remains on the highest level of readiness, she said, adding that it's time to end the "vicious cycle" of North Korea provoking security crises to win rewards from the international community.
But she also presented a vision for rapprochement and eventual reunification, which the North also seeks, but on socialist lines.
"I will remain steadfast in pushing forward a process of trust-building on the Korean Peninsula. I am confident that trust is the path to peace -- the path to a Korea that is whole again," she told lawmakers.
"But as we say in Korea, it takes two hands to clap."
Park is the daughter of the late South Korean dictator Park Chung-hee. In her 20s, she assumed the duties of first lady after a gunman claiming orders from North Korea killed her mother.
Park's attempts to build trust with North Korea have gained no traction, and relations have worsened since she took office. The North recently forced the closure of a joint industrial park that was a rare symbol of cooperation between the two countries.
But in a sign that tensions could be subsiding, U.S. officials reported Tuesday that North Korea has removed from a launch site two mobile, medium-range ballistic missiles that had been readied for possible test-firing.