The president of the Marshall Islands said on Wednesday that his Pacific island nation was "cautiously optimistic" it could soon finalize a deal on future ties with the United States, but repeated a call for Washington to address the legacy of massive nuclear testing in the 1940s and 50s.

The Marshall Islands is one of three sparsely populated Pacific island nations covered by so-called Compacts of Free Association (COFAs) with the United States. Under the agreements, the U.S. has responsibility for their defense and provides economic assistance, while gaining exclusive access to huge strategic swaths of the Pacific.

The U.S. agreed renewed COFA deals with Micronesia and Palau this year, but is still negotiating with the Marshall Islands at a time when China is making significant inroads into the Pacific, a region the U.S. has long considered its back yard.