Ahead of visit, U.S. and South Korea ties stronger than ever

(CNN) -- On the eve of meetings between President Barack Obama and South Korean President Park Geun-hye, a White House official says the recent saber rattling by North Korea has only strengthened the relationship between the allies.

Daniel Russel, White House special assistant and senior director for Asian affairs, told reporters on a conference call Monday Obama will use Park's visit to "reaffirm the strong commitment" of the U.S. to the defense of the Republic of South Korea.

Park will meet with Obama in the Oval Office Tuesday, followed by a working lunch and a joint news conference with the two leaders.

Monday a U.S. official confirmed to CNN that two North Korean Musudan missiles have been withdrawn from a launch site in the eastern part of the country and sent to a storage facility.

Last month, North Korean leader Kim Jong Un threatened to attack the United States, South Korea and Japan with nuclear weapons.

Russel told reporters it would be "premature" to make a judgment about whether the North Korean "provocation cycle is going up, down or zig-zagging." He said, "No one should be prepared to declare a victory yet," referring to the reports of North Korean missiles being moved off the launch sites.

Russel said Tuesday's meeting between Obama and Park would make it "crystal clear" the two leaders stand "shoulder to shoulder" in terms of policy toward North Korea.

Russel saying the U.S. and its partners would need to see "credible and irreversible steps" signaling a commitment on the part of North Korea to end their nuclear program and completely denuclearize the peninsula before the U.S. and its allies would consider adjusting sanctions against North Korea.

Tuesday's talks will also focus on economic cooperation between the U.S. and South Korea, as well as other political and security issues including Afghanistan, Syria, climate change and clean energy.

Park made history in February by becoming South Korea's first female president.