On December 17, 1996, Giampietri was taken hostage by the Túpac Amaru Revolutionary Movement (MRTA) during the Japanese embassy hostage crisis. Key to the success of the rescue operation was the intelligence provided by Giampietri, admiral of the Peruvian Navy at the time and former commander of a special operations group. He received and distributed hundreds of bugged items in the building and himself communicated by radio with the Peruvian military.