Secretary of State Rex Tillerson discussed the possibility of nuclear weapons on the island of Japan in an interview published Saturday, saying "circumstances could evolve" on the Korean peninsula that would require the U.S. to arm its ally with nukes.

"We say all options are on the table, but we cannot predict the future," Tillerson told the Independent Journal Review, the one news outlet allowed to accompany the secretary of state on his six-day Asia trip. "So we do think it's important that everyone in the region has a clear understanding that circumstances could evolve to the point that for mutual deterrence reasons, we might have to consider [a nuclear Japan]."

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Tillerson's comments came amid regional tension and after North Korea launched a series of missile tests, which included firing three missiles earlier this month that landed within 200 miles of Japan's coastline.

In response, Japan launched a spy satellite Friday to monitor the secretive communist country, which declared it developed a nuclear weapon in 2003. The U.S. has more than 20 military bases in Japan, a country that does not have nuclear capabilities.

While Tillerson opened the possibility of a nuclear Japan in his comments, he emphasized that official U.S. policy is to work towards fewer nuclear weapons in the region, not more.

"Our objective is a denuclearized Korean peninsula. A denuclearized Korean peninsula negates any thought or need for Japan to have nuclear weapons," Tillerson said. "Our objective is to have the regime in North Korea come to a conclusion that the reasons that they have felt they have had to develop nuclear weapons, those reasons are not well-founded."

North Korea continued its aggressive posturing during the final hours of Tillerson's Asia tour, which ended Sunday when he met Chinese President Xi Jinping in Beijing. On Sunday, state-run media in North Korea reported the country's military had successfully tested a high-thrust rocket engine.