By Stephen Costello

WASHINGTON ― The Singapore summit between the U.S. and North Korean leaders was an unqualified success. Much still remains to be done in order to follow up on the promises in the joint statement. This was to be expected.
The changed tone in the U.S.-North Korean relationship is critical, because that tone during 2017 alarmed the public in the U.S., Korea, East Asia and the world.
In addition, that tone was accompanied by a buildup of arms, a buildup of tensions, and a great expenditure of assets. That tone ― which was only an exaggeration of the previous tone for the past decade ― also prevented the economic, political and infrastructure development of the Northeast Asian region.
The personal and political value of the meeting of these two heads of state is impossible to calculate, but it is enormous. In both countries, the leader's investment marks a major shift away from confrontation and toward diplomacy, and a major shift toward simultaneous denuclearization and the lifting of sanctions surrounding North Korea.
The fact that the joint statement did not mention either the return of IAEA inspectors to North Korea or the lifting of economic sanctions by the U.S. suggests that these remain key early concrete steps that both can take. Movement on them will be a good guide to how successfully the follow-up negotiations proceed.
There are many signs that Chairman Kim Jong-un is serious about rolling back his nuclear weapons and long-range missiles in order to begin economic development, and he will have to be watched closely. His public statements and repeated messages since January, including front-page coverage and justifications for policy changes at home, are important and significant.
There are far fewer signs that the massive American foreign policy and national security bureaucracy can likewise follow the lead of Trump and his team in the coming months.
Assuming that national security adviser John Bolton has been contained, the coming policy and ideological fights between the White House and the State Department on one hand, and the U.S. Congress and foreign policy mainstream on the other, will be the biggest fights since Trump walked away from the Iran nuclear deal.
President Trump has done perhaps the only thing in his foreign policy that advances U.S. interests, supports and brings closer U.S. allies, and helps diffuse a longstanding issue of military tension and nuclear proliferation.
If this policy change is to survive beyond the next few months and beyond the end of Trump's term, a new coalition of political forces in Washington ― including practical and serious Democrats, arms control specialists, and think tank scholars ― will be required. Today it is very hard to imagine how such a coalition can be built.
It may well be that, as the next U.S.-North Korea meetings are scheduled, and the South Koreans begin to return to their role as guides and managers of this process, those fights within the U.S. will be the most hard-fought and the most dramatic.
Fights on similar terms are already well underway in South Korea, where the conservative party and its supporters have bitterly opposed the April 27 Panmunjeom inter-Korean summit agreement in the National Assembly. That group previously opposed the breakthrough South-North summit of 2000, preventing then conservative opposition lawmaker Park Geun-hye from accompanying President Kim Dae-jung to Pyongyang.
Similarly, U.S. conservatives, mainly Republicans, bitterly opposed the U.S.-North Korea agreement of 1994 which capped nuclear and missile production. Once Republicans were back in the White House in 2001, they helped destroy it.
Both countries' conservative blocs have resisted modernization, and have become ideological, narrow-minded, impractical and extreme regarding security policy. Fifty-year-old anti-communism continues to be an organizing principle for them.
Some Democratic and progressive members in both parliaments have been drawn into the zero-sum, over-hyped threat assessment rationale that supports conservative policies. A letter to Trump from some of these Democrats in the U.S. this week reveals their confusion.
In view of this, the political talents of both Donald Trump and Moon Jae-in will now be tested. Both must wrestle with these forces in order to make their upgraded and more strategically beneficial North Korea approaches into broad-based and durable national policy.
For South Korea, it is past time to actively drag the U.N., through U.N. Secretary General Antonio Guterres, into a more central role as facilitator for an adjustment of U.N. sanctions if and when there are continued North Korean denuclearization actions. The coalition for this logical role for the U.N. has been waiting for Seoul to organize it.
For Japan, its opportunity now is to quickly arrange a Tokyo-Pyongyang summit, get some accounting of the kidnapped citizens from the North, and put its enormous economic leverage on the side of denuclearization, development, arms reduction, and transparency.
For China, a continuation of backing and advice for Kim, together with the promise and reality of increased China-North Korea trade, all tied to his continued cooperation on denuclearization, will cement the new regional openness.
Still, after the Singapore summit the most important actions will be the rapid re-establishment of economic engagement with North Korea, by China, South Korea, Russia, and then others.
Stephen Costello (scost55@gmail.com) is a producer of AsiaEast, a web and broadcast-based policy roundtable focused on security, development and politics in Northeast Asia. He writes from Washington, D.C. A short version of the above article previously appeared in NNA/Kyodo Newswire Japan edited by Mr. Tetsuo Sakabe.