Washington will closely watch the Dec. 16 Lower House election and work with whichever party emerges victorious and forms Japan's new government, a U.S. State Department official said.

"We expect that we will work well with whomever the Japanese people choose to elect, and we will be following closely," State Department spokeswoman Victoria Nuland said Friday.

"We are the closest of allies. That is important for the United States, it's important for Japan, but it's also important for the region," Nuland said, adding Tokyo-Washington relations "will remain critical" to both sides.