The additional frequencies were authorized worldwide by the 2015 World Radiocommunication Conference (WRC-15) for a secondary allocation to amateurs. U.S. amateurs have been permitted to operate on five discrete channels within the band since 2003, and according to the ARRL, there have been zero reports of interference by amateurs to the primary federal users of the band.
Four of the five current
channels are outside the band segment authorized at WRC-15, and the ARRL asked
the FCC to retain those while adding the new segment. In addition, the League
asked the Commission to retain its current maximum power level of 100 watts PEP
effective radiated power for hams on 60 meters, rather than the 15-watt
effective isotropic radiated power limit set by WRC-15.