He, however, stressed that this is only one of the potential options, taking into account possible developments.

In comments to Independent Review Jornal Tillerson pointed out that Washington's main purpose remains the curtailment of North Korea's nuclear programme. "And a denuclearized Korean Peninsula removes any thought about the appearance in Japan of nuclear weapons or the need for this," he said.

However, he continued, the U.S. "can't predict the future". "Therefore, we believe it is important that everyone in the region had a clear understanding of what circumstances may reach the point where for reasons of mutual deterrence we might have to consider it," Tillerson was quoted by TASS.