South Korea announced last weekend that the UN Security Council had finally granted an exemption from sanctions for its plans to work with North Korea on a joint survey as the first step towards reconnecting rail and road links between the two Koreas severed during the Korean War of 1950–53.

While the US did not use its veto in the UN Security Council to block its ally, the Trump administration is increasingly dissatisfied with moves by South Korean President Moon Jae-in to foster closer relations with North Korea prior to a deal on its denuclearisation. Washington effectively delayed the planned survey in August, and again last month, by declaring that it could violate UN sanctions.

Trump is insisting that the US will not lift punitive sanctions on North Korea until it has met his demands for the dismantling of its missile and nuclear arsenals, production facilities and programs. He met with North Korean leader Kim Jong-un in Singapore in June which produced a vaguely-worded, joint statement agreeing to “the denuclearisation of the Korean Peninsula” in return for unspecified security guarantees from the US.

The US has wound back its joint military exercises with South Korea, and North Korea has halted all missile and nuclear testing. However, after more than five months, talks between the US and North Korea have stalled. Washington has rejected North Korean calls for moves towards a peace treaty to formally end the Korean War and a step-by-step lifting of sanctions in return for moves to denuclearise.

A meeting earlier this month between US Secretary of State Mike Pompeo and his North Korean counterpart Kim Yong-chol was cancelled. Last week a North Korean website criticised the failure of the US to make any concessions. “These acts by the US apparently came from a medieval-era way of thinking that only threatening, coercive and barbarian tactics could enhance its negotiating leverage,” it stated, adding that such tactics would not work.

South Korean President Moon, however, is keen to improve relations and reduce tensions with North Korea, which last year were threatening to engulf the Korean Peninsula in war. Speaking at the UN, Trump belligerently warned that North Korea faced “total destruction” if it threatened the United States.

At a summit in April, Moon and North Korean leader Kim agreed to take practical steps towards reconnecting the rail and road systems of the two countries. South Korea offered to renovate North Korea’s rail system and to send a train and engineers across the border to conduct a joint survey, to which North Korea agreed.

Re-establishing transport links is just part of the Moon administration’s broader plans to economically integrate the economies of the two Koreas. His Democratic Party has long been associated with the so-called Sunshine Policy aimed at transforming North Korea into a cheap labour platform for South Korean conglomerates.

Following the weekend announcement of a UN sanctions exemption, shares in South Korean companies linked to rail construction increased sharply—Korea Engineering Consultants and Yooshin Engineering by 30 percent. An IBK Economic Research Institute report this year estimated that the government’s plans for economic engagement with North Korea could increase South Korea’s GDP by more than 1 percent.

Rail, road and pipeline links through North Korea to China, Russia and on to Europe were central to the Sunshine Policy of President Kim Dae-jung. However, US President George Bush sabotaged these plans on assuming office in 2001 when he called for a review of US policy towards North Korea and scuttled the 1994 Agreed Framework to end Pyongyang’s ambitions to build nuclear weapons.

President Moon has also taken steps to ease military tensions with North Korea at the Demilitarised Zone (DMZ) that separates the two Koreas. Agreements were reached during talks in September to dismantle all guard posts and halt live-fire exercises along the DMZ, and disarm and limit the number of troops from both sides in the shared border village of Panmunjom. This month North and South Korea have each demolished 10 guard posts.

The Trump administration, however, has expressed its concerns about warming relations between the two Koreas. Last week Secretary of State Pompeo warned South Korea “to make sure that peace on the peninsula and the denuclearisation of North Korea aren’t lagging behind the increase in the amount of inter-relationship between the two Koreas.” He was speaking after a joint working group with South Korea to “coordinate” North Korean policy—that is, to ensure that Seoul toes Washington’s line.

While the Moon administration has not openly opposed or criticised the Trump administration’s hard-line stance towards North Korea, there is frustration in government ranks over US intransigence. “As long as this lack of confidence persists, the United States and North Korea will just be going around in a vicious circle,” Lee Soo-hyuck, a former South Korean negotiator and government lawmaker, told the Washington Post recently.

The Trump administration, however, shows no sign of making any concessions to North Korea. Earlier this month the US military provocatively held small-scale military drills with South Korea involving altogether 500 Marines. Last week, US Defence Secretary James Mattis foreshadowed that the annual joint Foal Eagle war games would proceed next year, albeit “reduced in scope” so as to keep from “being harmful to diplomacy.”

The Foal Eagle military drills are clearly a rehearsal for war with North Korea. Although delayed this year so as not coincide with the Winter Olympics in South Korea, these war games involved more than 300,000 US and South Korean troops backed by artillery, heavy armour, warships and military aircraft.

If the exercises proceed next year, they will certainly provoke an angry response from Pyongyang. While North Korea has frozen its nuclear and missile testing and destroyed the entrances to its nuclear test site, the only step taken by the US has been to wind back its joint military drills. North Korea is desperate for an easing of UN and US sanctions which have blocked much of its trade and crippled its economy.

While a second summit between Trump and North Korean leader Kim has been mooted, nothing has been announced. Instead, Vice President Mike Pence told NBC News that if Kim is to meet Trump, it is “absolutely imperative” that he hand over a verifiable plan to disclose nuclear and missile sites, open them for inspection and dismantle them.

Such ultimatums threaten a return to extreme tensions on the Korean Peninsula and to destroy South Korean efforts to improve relations with North Korea.