President Donald Trump’s approach to North Korea was defined by “tough” talk, threats and very little follow-through. It’s safe to say that many foreign policy analysts, particularly North Korea watchers, welcome a fresh start in January.

Biden’s previous executive branch experience was as part of an administration that was cautious – many would say to a fault – but this meant no preemptive military action, hollow summit declarations or deals that the U.S. couldn’t back out of if the North did not honor them.

In fact, Biden has given little indication that he wants to repeat any of Trump’s actions on the peninsula: He has called Kim a “thug” and said that he would not meet with him unless North Korea commits to some denuclearization steps first, and he is certain to abandon Trump’s demands that South Korea and Japan drastically increase their financial commitments to the alliance.

Recently, it has also been suggested that Biden will reestablish an envoy for human rights — a move unlikely to change the strategic calculus on the peninsula, but very likely to infuriate the regime. Meanwhile, Biden seems unlikely to offer sanctions relief in the near future.

However, much has changed since Biden’s time in the Obama administration — not just in terms of U.S.-North Korea relations, but also in terms of South Korea’s presidential Blue House. Former President Park Geun-hye’s administration wanted to dictate the terms of its denuclearization before any cooperation with Pyongyang would proceed, and when the North rejected that idea, Park sought to turn Pyongyang’s partners against it. She supported a resolution condemning its human rights record at the U.N. and ended the economic cooperation in place.

Whatever the differences between Obama and Park, their approaches to North Korea rarely, if ever, rubbed the other one the wrong way.

This matters because, after the Trump administration’s attempt to strong-arm Seoul into paying more for U.S. military presence, Biden’s team has made it clear that improving ties with South Korea is a foreign policy priority. And it’s here that we can see a potential contradiction emerge in Biden’s approach, as the incumbent Moon administration — contra Park — has floated several ideas for cooperation with the North that would not require concessions on its nuclear program and human rights record. Reports suggest that Seoul is optimistic that Biden will allow South Korea to continue its overtures to the North.

It would be one thing if Seoul and Washington were content to play good cop-bad cop, with the U.S. drawing a hard line, highlighting the North’s human rights record and maintaining deterrence while South Korea promotes the benefits that would emerge out of economic cooperation. This strategy might not – okay, probably would not – produce any great dividends right away, but it would reveal to the world that the alliance remains strong and that North Korea, not the South or the U.S., is the recalcitrant party.

The problem is that neither North or South Korea are likely to appreciate such an arrangement.

South Korea wants economic cooperation in the short term, and not just because of dreams of a reunified Korean nation. A hostile North is literally an obstacle to integration with Eurasia and the economic opportunities that could emerge.

North Korea’s outburst from this spring – in which it demolished the inter-Korean liaison office and denounced South Korea so harshly that the ever-collected, ever-conciliatory Moon began to threaten countermeasures – shows that Pyongyang will not be happy if U.S. sanctions continue, or if South Korea failures to secure relief from them.

Consequently, Joe Biden’s administration looks all but certain to face pressure to reverse Trump-era (and beyond) sanctions, or at least grant waivers to South Korea. North Korea’s return to nuclear testing could very well resume and potential border skirmishes look very possible, as well — underscoring once again how South Korea bears the brunt of Washington’s North Korea policy.

Biden will certainly face accusations that he is placing American interests ahead of Koreans’ wishes for peace, along with new fears of war and his predecessor chirping on social media that he was right, and that no other administration can deliver Korean peace.

Biden should be aware of this, because the consequences of lifting sanctions would be long-lasting and the salutary effects short-lived.

There’s plenty of evidence suggesting North Korea will never denuclearize and will cheat on any deal it accepts. Certainly, Pyongyang’s spring antics show that it reserves the right to resort to provocations any time it chooses and against any one, no matter how compliant.

By dumping sanctions and letting Seoul proceed as it will, Biden might also vindicate some of the Moon administration’s worst behavior, such as ratcheting up Japan tensions and cracking down on defector-led organizations. Biden should also not be persuaded by the idea that he would be denying the Korean people their desire for unification – Moon Jae-in does not owe his overwhelming victory in 2017 to a pro-unification platform, but to public disgust with Park Geun-hye’s scandals. Most South Koreans value the U.S. alliance, and while they certainly do not want a war, their opinions of North Korea show no real urgency for unification.

Biden should make clear his limits with the South early on. Otherwise, the emerging contradictions in his approach may explode into the open in early 2021 – and not only in a figurative sense.

Edited by Kelly Kasulis