Amid media hype, a South Korean train penetrated North Korea on Friday on a mission to investigate the North’s rail infrastructure – an essential step before any eventual reconnection of the two country’s transport nets across the Demilitarized Zone.

However, Friday’s upbeat optics masked underlying tensions.

North Korea is impatient with the pace of engagement with its southern neighbor, which – shackled by international sanctions and its alliance with the United States – is unable to implement commercial or economic projects.

Meanwhile, Seoul’s dalliance with Pyongyang irks its US ally, which wants the pace of engagement slowed unless and until Pyongyang starts making serious moves on denuclearization. High-level talks between Pyongyang and Washington on that issue have been frozen since October.

The current situation presents South Korean President Moon Jae-in with a diplomatic balancing act of extreme delicacy.

Full steam ahead

Still, these tensions were not apparent on Friday.

“Through the one connected railway, the South and the North will prosper together and the ground for peace on the Korean Peninsula will be consolidated,” gushed Unification Minister Cho Myoung-gyon in a televised message. “The trains running on the track will also carry peace and prosperity with them to Northeast Asia and the world.”

TV news reporters accompanied the train from Seoul Station to Dorasan, a station on the west side of the peninsula and immediately south of the Demilitarized Zone. Once in the North, the 18-day reconnaissance mission will inspect more than 1,000 kilometers of North Korean track, according to Seoul’s Ministry of Unification.

The train’s six cars, packed with South Korean officials, contain living quarters and office facilities. The UNSC granted Seoul a sanctions waiver to take certain items into the North. In the absence of an electric grid for North Korea’s tracks, the South Korean electrical engine was to be replaced by a diesel locomotive inside the North.

The North’s railway system is widely dilapidated. Travelers complain of slow speeds and long waits. Disasters have also struck: The city Ryongchon was devastated in a still-mysterious rail station explosion in 2004, and travelers report seeing a shattered coach at the bottom of a valley in the northeast.

This suggests that bringing the North’s rail net up to scratch could cost billions. Those are billions Seoul may be willing to spend, as a rail reconnection via North Korea would link South Korea – a de facto island – with the Eurasian landmass, enabling South Korean cargo to enter the trans-China and trans-Siberian networks, accelerating shipment times.

However, it cannot spend those billions at present. And deju vu pervaded Friday’s event.

A missing link

Much coverage overlooked the fact that cross-border rail lines were relinked, amid great fanfare, in 2007. That took place in the last year of the liberal Roh Moo-hyun administration. Roh left office in 2008 and was replaced by conservative Lee Myung-bak.

Lee’s disinterest in the “Sunshine Policy” of engagement irked Pyongyang and the last cross-border cargo train ran in 2008. In 2010, North Korea initiated deadly clashes against South Korea in the Yellow Sea.

Seoul enacted sanctions that year, preventing South Koran companies from doing business in the North, beyond a single inter-Korean industrial complex at Kaesong. Work at Kaesong was halted by Seoul in 2016 amid security tensions under the Park Geun-hye administration that succeeded Lee.

With the liberal Moon in the Blue House and Lee and Park in the jailhouse serving hefty sentences for corruption, inter-Korean cooperation is a national agenda item again. Now barely a day goes by without the announcement of some inter-Korean project: The provision of fertilizer aid; sports or cultural exchanges; talks on military tension-reduction efforts.

What is glaringly missing amid all ongoing engagement fever is any economic substance.

Adherence to sanctions

Since 2010, inter-Korean business has dried up. Now, with harsh UN Security Council Sanctions also in place – and the fear of being targeted by US Treasury secondary sanctions – it is virtually impossible for South Korea to engage economically in North Korea, even if Seoul lifted its own bilateral sanctions, as has been discussed but not implemented.

The Moon administration, keen to keep US President Donald Trump in play, makes much of its adherence to sanctions. It has launched probes into Russian coal and iron, which turned out to be re-exported from North Korea, and has touted the UNSC’s approval of Friday’s train trip.

But even that last point indicates unspoken tensions. In August, the US-led UN Command in South Korea stopped a Southern train, which had the same mission as Frday’s, from entering the North.

Further unease is apparent in commerce, with trammeled South Korean companies eager to rapidly establish bridgeheads in the North. “The Ministry of Unification expressed that the priority is to enter the North Korean market and establish goodwill with North Korean counterparts as early as possible,” said Go Myong-hyun of Seoul think tank the Asan Institute.

“If not, [North Korea’s market] will be taken over entirely by China.”

Seoul, enmeshed in a security alliance with Washington, cannot side diplomatically with Beijing and Moscow, which favor eased sanctions on Pyongyang. “We are saying we are in the drivers’ seat, but we all know it is a compromise between the US and South Korea,” said Choi Jin-wook, a North Korea expert at Hankook University of Foreign Studies. “It cannot be our sole decision.”

Moon, during an October tour of Europe, attempted to win support from UNSC members France and the UK for eased sanctions on North Korea. He was rebuffed by Emanuel Macron and Teresa May.

Regardless of his diplomatic frustrations, Friday’s good vibes contain some positives for Moon. “The reason why Seoul is focused on the optics of dialogue and engagement is the domestic audience, as [North Korea engagement] is important politically for the standing of the government,” Go said. “And this acts as pressure on the US.”

Moon is expecting to welcome Kim Jong Un on an historic trip to Seoul in December for what would be their fourth summit. But without progress on sanctions, it is unclear what the two can discuss. The best possibility for progress now lies in the proposed second summit between Kim and Trump, slated for next year.

Yet, amid stalled talks, it is not even clear if that will take place. “Before the second Kim-Trump summit, we need a lot of things to be resolved,” said Choi. “If there is no progress at working-level or high-level talks, there may be no second summit.”

Absent a North Korea-US breakthrough, Moon’s dual-track strategy of optically engaging Kim while keeping Washington onside cannot continue indefinitely.

“This is not sustainable: South Korea has written a lot of blank checks to everyone and all those checks are bouncing,” said Go. “Moon understands the challenge of lifting sanctions without progress on denuclearization. Next year, he will have to make a decision. Risks are going up.”