In language usually reserved for more restive parts of the world, Japan's top government spokesman on Thursday said Tokyo was concerned and closely monitoring the breach of the U.S. Capitol by supporters of President Donald Trump.

"We are hoping for a peaceful transfer of power" in the United States, Chief Cabinet Secretary Katsunobu Kato told reporters.

The United States' key Asian ally joined a chorus of world leaders in voicing alarm over the breach, with the U.K. and Australia also calling for a peaceful transfer of power and allies in Europe calling the protesters’ actions an attack on democracy.