Victoria Nuland, a spokeswoman for the U.S. State Department, confirmed that Clinton is leading the highest-ranking delegation to the Pacific Islands Forum in more than 40 years.
"We have been emphasizing the pivot to Asia for some time now" she said. "The secretary is personally very invested in that."
Cook Islands Prime Minister Henry Puna said the PIF summit would focus on regional unity for the community of small island nations.
"I believe that our large ocean island states should demonstrate now more than ever a renewed commitment to defining our future on our terms and in our own Pacific way," he was quoted by China's official Xinhua News Agency as saying.
Nuland said Clinton's visit was likely her third to the region this year.
Washington has expressed concerns about China's influence in the region. U.S. Deputy Secretary of Defense Ashton Carter said at the end of a tour of the region early this month that a continued focus on the Asia-Pacific region was "one of the most prominent and important" issues for the Department of Defense.