The chairman of the U.S. Joint Chiefs of Staff met Prime Minister Shinzo Abe and the Japanese Self-Defense Forces' top officer in Tokyo on Friday, discussing with both the increase in tensions over North Korea.

At the outset of his meeting with Abe, Marine Corps Gen. Joseph Dunford told the prime minister that "the nature of our bilateral relationship, particularly at the military level, is rock solid."

Abe told Dunford he wants to work together to bolster the Japan-U.S. alliance, noting the threat from North Korea, which last week said it was considering launching ballistic missiles over the Japanese archipelago to waters near Guam, a U.S. territory in the western Pacific.

"I highly appreciate the fact that (U.S.) President (Donald) Trump has made clear that the United States will take every necessary measure to protect its allies regarding the North Korea issue," Abe said.

Earlier Friday, Dunford met with Adm. Katsutoshi Kawano, chief of the SDF Joint Staff, and the two affirmed the importance of cooperation between the Japanese defense force and the U.S. military to address the threat posed by North Korea.

According to a statement released by the Joint Staff, Dunford told Kawano in their meeting at the Defense Ministry that "the U.S. commitment to the defense of Japan including extended deterrence remains ironclad."

In Washington on Thursday, Japanese and U.S. foreign and defense ministers agreed in their "two-plus-two" talks to strengthen the Japan-U.S. alliance to respond to the increased threat from North Korea's nuclear and ballistic missile development efforts.

Before arriving in Japan, Dunford visited South Korea and China, meeting with South Korean President Moon Jae In and Chinese President Xi Jinping as well as military officials.