President Barack Obama is sending the group to Saudi Arabia days after the burial of late Crown Prince Nayef, who died suddenly last week after less than a year as the designated successor in the oil kingdom.
Saudi Arabia has already announced a new No. 2, the country's current defense minister and another of the elderly sons of the country's patriarch.
Panetta, White house counterterrorism chief John Brennan, FBI director Robert Mueller and others will pay respects to 88-year-old Saudi King Abdullah on Wednesday.
Saudi Arabia is OPEC's top oil exporter and one of the West's main Middle East allies .