SEOUL, South Korea — Diplomacy aimed at ending the North Korean nuclear crisis has produced little tangible progress since the historic June 12 summit between President Donald Trump and North Korean leader Kim Jong Un.

North Korea hasn't taken any serious steps toward dismantling its nuclear weapons, which it has long said would deter any U.S. attempt to invade. The United States recently announced the suspension of military drills with South Korea but is reluctant to offer more concessions unless North Korea starts denuclearizing.

A look at what Washington wants North Korea to do and vice versa as U.S. Secretary of State Mike Pompeo arrives Friday in Pyongyang for two days of talks.

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U.S. DEMANDS

The United States wants North Korea to dismantle its nuclear and missile programs entirely, but achieving that appears extremely difficult.

Before the June summit, North Korea imposed a moratorium on its nuclear and missile tests, shut down its nuclear test site and released three American detainees. These moves helped build budding ties with the United States, but many experts say North Korea must take much stronger steps to prove it's serious about denuclearization.

During Pompeo's trip, North Korea could follow through on its earlier agreement to return the remains of U.S. soldiers killed during the 1950-1953 Korean War, but it's unclear what denuclearization measures the country would agree to.

North Korea likely won't fully trust Trump's promise to provide the country with a security guarantee and can easily hide some of its nuclear assets in its extensive network of underground facilities.

Some experts expect the North to agree to shut down its main nuclear complex near Pyongyang and give Pompeo a list of detailed denuclearization steps it would take in the coming months. Others say no major breakthrough is expected, but the two countries would agree to meet again, because they have gone too far to pull out now.

To keep nuclear diplomacy alive, Pyongyang must soon dismantle its nuclear warheads, nuclear materials such as weapons-grade plutonium or uranium, and long-range missiles or ship them to the U.S., according to analyst Cho Han Bum at Seoul's Korea Institute for National Unification.

Go Myong-Hyun of the Seoul-based Asan Institute for Policy Studies said the United States may focus on demanding the dismantling of missiles, whose size makes them harder to conceal than warheads and nuclear materials.

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NORTH KOREAN DEMANDS

In years past, North Korea has set a list of preconditions for its nuclear disarmament. They include the United States withdrawing its 28,500 troops in South Korea, ending its military drills with South Korea and stop bringing in strategic assets such as aircraft carriers and nuclear-capable bombers.

North Korea hasn't repeated such specific demands since entering disarmament talks earlier this year, raising optimism that the country truly appeared to seek to improve ties with the United States. After the summit, Trump suspended annual military training with South Korea that the North has called an invasion rehearsal.

But North Korea still prefers a step-by-step disarmament process with reciprocal concessions and benefits from the United States for each of the North's denuclearization steps. The ultimate rewards North Korea wants range from the easing or lifting of American-led international sanctions, the signing of a peace treaty to formally end the Korean War, the establishment of diplomatic ties and the pulling out of U.S. troops in South Korea, experts say.

During Pompeo's visit, North Korea is expected to ask the United States to consider signing a peace treaty to prolong a peace mood and find ways to seek sanctions relief, Go said.

Whatever U.S. concessions and rewards North Korea gets, however, some experts say North Korea will likely push to scrap only some of its nuclear capability, not all. They believe North Korea thinks Trump would settle for a partial denuclearization deal to avoid a total failure in his North Korea policy in the face of political woes at home.

"Kim Jong Un would think the ball is now in Washington's court and that he doesn't need to be in a hurry," said Nam Sung-wook, a professor at Korea University in South Korea.