Finance Minister Katsunobu Kato said the country’s U.S. Treasury holdings could be a card in its trade talks with Washington, referring to the largest stockpile of U.S. debt held by a foreign nation.

"It does exist as a card,” said Kato, speaking on a TV Tokyo program Friday, when asked if Japan’s stance of not selling holdings could be a negotiation tool. "Whether or not we use that card is a different decision.”

While the comments were made in response to a question and don’t appear to suggest Japan is considering selling any of its U.S. Treasury holdings, they open up the possibility of large market ructions if action took place.