Prime Minister Shinzo Abe and the U.S. Army's chief of staff confirmed Monday that Japan and the United States will work more closely with each other and with South Korea in dealing with North Korea.

Abe and U.S. Army Chief of Staff Gen. Mark Milley agreed in Tokyo on the importance of maximizing pressure on North Korea to bring about its complete, verifiable and irreversible denuclearization, the Foreign Ministry said in a statement.

At the outset of the meeting, Abe said that based on his discussions on North Korea with U.S. President Donald Trump and Vice President Mike Pence, "Japan and the United States are in step with each other and in complete agreement about how to deal with this issue."

"The alliance between the United States and Japan is extraordinarily important to my country, it's rock solid, and we stand shoulder-to-shoulder with Japan, the Japanese people and Japanese military, along with the people of South Korea, in the face of an increased and growing threat from North Korea," Milley said.

Milley told Abe he plans to go after the meeting to Iwoto Island -- an islet some 1,200 kilometers south of Tokyo previously called Iwojima -- on the anniversary of the U.S. forces' landing in 1945 in what became one of the fiercest battles of World War II. He said his father was among those who fought on the island.

Ahead of his meeting with Abe, Milley also met Defense Minister Itsunori Onodera at the Defense Ministry.

Onodera told Milley that North Korea "has not changed at all its development of nuclear weapons and missiles, despite displaying 'smile diplomacy' at the Pyeongchang Winter Olympics in South Korea."

As a member of the Joint Chiefs of Staff, Milley advises the president, defense secretary and National Security Council. He has been in the role since August 2015.