While differences over whether Japan has adequately atoned for its imperial history remain, the meeting between Japanese Prime Minister Shinzo Abe and South Korean President Park Geun Hye yesterday means Ms Park has finally conceded that such differences ought to be discussed bilaterally. This is in happy contrast to Seoul's prior stance that the existence of such differences precluded any bilateral summit with her Japanese counterpart.
Even so, both countries know the hard work is only just beginning. But Tokyo and Seoul should also be aware that there is more at stake than simply good relations between two North-east Asian neighbours. The region has much to gain from a genuine thawing of relations between the two capitals, and much to lose should the relationship slide back into animosity.
That Japan and South Korea have much in common when it comes to their interests in the region should be immediately obvious.
The two countries are allies of the United States, even if they are not allies with each other. Both seek to work within their respective alliances with the US to constrain the behaviour of a nuclear-armed North Korea, and deter the latter from actions which might threaten or destabilise the entire region.
Managing its troublesome northern neighbour is still Seoul's highest strategic priority. This is why Ms Park's previous criticism of Mr Abe's more ambitious strategic plans for Japan in the region was counter-productive.
As the lead partner, Washington still needs a more can-do and will-do Japan as a force multiplier to better restrain Pyongyang. In contrast, a timid Japan will place additional pressure on Washington's already strained Seventh Fleet in the Pacific Ocean.
Then there is the dilemma of China, which is neither a true friend nor yet a foe of America and its East Asian allies and partners.
There has been considerable discomfort in Washington and other Asian capitals such as Tokyo, Singapore and Kuala Lumpur that Ms Park had met China's President Xi Jinping one-on-one half a dozen times even as she refused meetings with Mr Abe.
While a hot war between China and the US remains unlikely - even if it is conceivable over issues in the Korean Peninsula, the Taiwan Strait or the East and South China seas - growing Chinese power and the way such power is being exercised is starting to challenge the existing US-led security system based on bilateral alliances and partnerships with Washington.
It is in the region's enduring interest that the US-led alliance system should remain robust even as it adapts to China's rise. And with Japan as the only strategic and military player in Asia that can rival China, the US-Japan Mutual Defence Treaty is the single most important strategic relationship within the regional alliances network.
By spurning summits with Tokyo and joining with Beijing to use history in the first part of the previous century to condemn a more proactive strategic role for Japan, Ms Park was inadvertently playing into Chinese hands by weakening the contribution that Japan can bring to the table within the alliance with America.
But by taking a more agnostic position vis-a-vis the emergence of a more pro-active Japan, Seoul would be denying Beijing a vehicle through which to undermine America's most important security relationship.
It is not all about geopolitics. At stake is the preservation of a so-called liberal system of economic rules which has allowed the greatest explosion of wealth compared to any other region in the second half of the previous century.
An open and liberal economic system does not predetermine who the winners and losers might be. In this sense, China's accusations that this is designed to suppress its economic rise make little sense, especially since it has been the biggest beneficiary of such a liberal order over the past few decades.
But a liberal economic order does insist on rules as to how nations and individual firms compete. This includes rules about protecting and respecting intellectual property and promises to allow market access to outsiders based on multilateral and bilateral agreements.
More broadly, liberalism demands a broad separation between national and political objectives on the one hand, and the commercial activity and goals of firms on the other.
While Japan and South Korea first emerged as authoritarian systems after World War II, they now exist as paragons of reformed liberal political economies that are not only prosperous, but have also made enormous contributions to prosperity in the region.
China has emerged as the leading trade partner for both these and many other countries in volume terms even if the majority of its trade in the region is assembling or modifying products for export to end-consumers in mainly advanced economies.
But Japan and South Korea remain the leading Asian exporters of innovation, advanced technology and know-how to the region - the prerequisite for any country, including China, to escape the dreaded middle-income trap and become an advanced economy.
It is no surprise that these two countries remain the two largest Asian sources of foreign direct investment in the region, while China is still a minor player in this regard. The point is that through cooperation within existing economic and trade agreements, and prospective ones such as the Trans-Pacific Partnership, Japan and South Korea are better positioned to collectively pressure China and other countries to abide by agreed rules than each might imagine individually.
Cynics might point out that nothing tangible was achieved at yesterday's summit. But, for once, the cliche is true: Leaders from both countries are at least now talking. And this should bring cautious optimism to the region.