Somali pirates have released two South Korean-owned fishing boats held since May in waters off the Horn of Africa.
The waters off Somalia's coast are notorious for piracy
The two boats and their 24 Asian crew members were escorted to safe waters by the US navy.
US naval personnel later boarded the vessels and gave the crew medical check-ups, said a US spokeswoman, Cdr Lydia Robertson.
The South Korean foreign ministry says the boats are now heading for Yemen and that the crew members are safe.
The crew members include 10 Chinese, four South Koreans, three Vietnamese, three Indians and four Indonesians.
Cdr Robertson said the US navy was also urging pirates on three other ships to leave the vessels and return to Somalia.
The waters off Somalia's coast lie close to crucial shipping lanes and are notorious for piracy.