SEOUL/WASHINGTON (Reuters) - North Korea has expressed its commitment to “complete denuclearization” of the Korean peninsula and has not attached conditions, South Korea’s president said on Thursday, but Washington remains wary and has vowed to maintain “maximum pressure” on Pyongyang.

South Korean President Moon Jae-in said agreements about denuclearization, establishing a peace regime and normalization of relations between the Koreas and the United States should not be difficult to reach through a North-South summit next week, and a later summit planned between North Korean leader Kim Jong Un and U.S. President Donald Trump.

“I don’t think denuclearization has different meanings for South and North Korea. The North is expressing a will for a complete denuclearization,” Moon said during a lunch with chief executives of Korean media companies.

“They have not attached any conditions that the U.S. cannot accept, such as the withdrawal of American troops from South Korea. All they are talking about is the end of hostile policies against North Korea, followed by a guarantee of security.”

CIA Director Mike Pompeo met Kim this month to discuss a proposed summit with Trump and reported that the North Korean leader was not demanding the withdrawal of all U.S. forces as a precondition for the meeting, a U.S. official briefed on Pompeo’s trip told Reuters.

However, the official, who did not want to be identified, said that while Kim was open to negotiating “denuclearization,” the term remained undefined and potentially deceptive, given the need for a timetable and an inspection regime.

North Korea has defended its nuclear and missile programs in the face of worldwide condemnation and sanctions as a necessary deterrent against perceived U.S. hostility.

It has said over the years that it could consider giving up its nuclear arsenal if the United States removed its troops from South Korea and withdrew its so-called nuclear umbrella of deterrence from South Korea and Japan.

On Wednesday, Trump, who says he plans to meet Kim in late May or early June for an unprecedented summit to try to persuade him to give up his nuclear weapons, reaffirmed the “unwavering” U.S. commitment to maintain that umbrella.

In a joint statement after talks with Japanese Prime Minister Shinzo Abe, Trump said the U.S. commitment to defend Japan “through the full range of U.S. military capabilities” was “unwavering”.

They reiterated their commitment to the “permanent and verifiable denuclearization of North Korea” and the need for Pyongyang to abandon all of its weapons of mass destruction and ballistic missile programs, while vowing stepped up sanctions enforcement.

The United States stations 28,500 troops in South Korea, a legacy of the 1950-53 Korean War, which ended in a truce, not a peace treaty. Trump complained in his election campaign about the cost of keeping those in Korea but his administration has given no indication of any plan to withdraw them.

South Korea announced on Wednesday it is considering how to change a decades-old armistice with North Korea into a peace agreement as it prepares for the North-South summit this month.

South Korea's President Moon Jae-in is seen during a meeting with Vietnam's Prime Minister Nguyen Xuan Phuc (not pictured) at the Government Office in Hanoi, Vietnam March 23, 2018. REUTERS/Kham/Pool

Moon said he saw the possibility of a peace agreement, or even international aid for North Korea’s economy, if it denuclearizes.

But he also said the inter-Korean summit had “a lot of constraints”, in that the Koreas could not make progress separate from the North Korea-United States summit, and could not reach an agreement that transcends international sanctions.

“So first, the South-North Korean summit must make a good beginning, and the dialogue between the two Koreas likely must continue after we see the results of the North Korea-United States summit,” Moon said.

Trump said on Wednesday that Pompeo formed a “good relationship” with Kim when he met him in Pyongyang and the U.S. President said he hoped the summit would be successful. But Trump warned he would call it off if he did not think it would produce results.

Trump told a joint news conference with Abe that his campaign of “maximum pressure” on North Korea would continue until Pyongyang gave up its nuclear weapons.

In Geneva on Thursday, U.S. Disarmament Ambassador Robert Wood told a news conference North Korea must show that it is “serious about getting rid of its nuclear weapons program” and take “concrete steps”, adding: “We’ve got a long way to go”.

China’s foreign ministry spokeswoman Hua Chunying told a regular press briefing in Beijing that China supported ending the state of war on the Korean peninsula.

“China supports ending the war state on the peninsula at an early date,” she said. “As a party involved in the peninsula issue, China is willing to play an active role.”

Ahead of next week’s summit, Seoul and Pyongyang will also complete the installment of a telephone hotline between the two leaders on Friday, directly connecting the South’s presidential Blue House and the North’s State Affairs Commission, the South’s presidential spokesman said.

Six top South Korean officials will accompany Moon to the summit, including his chief of staff, spy chief, national security adviser and unification, defense and foreign ministers, the spokesman said.

North Korea meanwhile will hold a plenary meeting of its ruling party’s central committee on Friday, state media KCNA said on Thursday.

The meeting was convened to discuss and decide “policy issues of a new stage” to meet the demands of the current “important historic period”, KCNA said.