WASHINGTON - U.S. Defence Secretary Robert Gates says he can't imagine dropping relief aid into Myanmar without the military junta's permission.

Another U.S. official says the U.S. is looking at that possibility, to help victims of the devastating cyclone in Myanmar. Gates says the military is moving aircraft and ships into place to help deliver humanitarian supplies once permission is granted.

But he says he can't imagine doing it without the Myanmar government's go-ahead.

Chairman of the U.S. Joint Chiefs of Staff Adm. Mike Mullen says it's a matter of Myanmar's national sovereignty.