WASHINGTON (XINHUA) - US Secretary of Defence James Mattis reaffirmed on Saturday (April 28) the commitment to defend South Korea, voicing support to diplomatic solution to the Korean Peninsula issue.

Mr Mattis reiterated "the ironclad US commitment" to defend its ally "using the full spectrum of US capabilities" in phone discussion with his South Korean counterpart Song Young Moo on the results of last Friday's inter-Korea summit, Pentagon chief spokesman Dana White said a statement.

The two defence chiefs also expressed commitment to a diplomatic resolution that achieves "complete, verifiable, and irreversible" denuclearisation of the Korean Peninsula, as reflected in multiple UN Security Council's resolutions, the statement said.

In his conversation with Mr Mattis, Mr Song reviewed the Panmunjom Declaration and the efforts to improve inter-Korea relations while achieving denuclearisation.

The Panmunjom Declaration for Peace, Prosperity and Unification of the Korean Peninsula, signed last Friday by South Korean President Moon Jae In and North Korean leader Kim Jong Un, pledged joint efforts for national reconciliation, denuclearisation and lasting peace.

Last Friday, Mr Mattis said the United States will discuss with its allies and North Korea the need for US troops to stay stationed on the peninsula.

The United States "will build, through confidence-building measures, a degree of trust if it's going to go forward". he added, referring to the dialogue with North Korea on denuclearising the peninsula.

The US troops have stayed in South Korea ever since the signing of the Korean War armistice treaty in 1953. Bilateral relations are often strained over issues such as defence burden sharing, the US army's harassment of South Korean civilians and Seoul's initiative to take back the war-time command control from Washington, among others.