The variety of regionalism in East Asia consists of an overlapping selection of bilateral, multilateral, and “mini-lateral” (three or more-sided subsets of existing multilateral) cooperative groupings in the diplomatic, economic, and military realms, with variations in membership and scope. Among the “ASEAN Plus” multilateral regional forums anchored on ASEAN, the most prominent are the ASEAN Regional Forum (ARF), ASEAN Plus Three (APT), East Asia Summit (EAS), and ASEAN Defense Ministerial Meeting Plus (ADMM+).

The involvement of China and Japan in these groupings may be described as having passed through all or some of three stages: attempts at cooperation, mutual tolerance amid rivalry, and pro forma attendance or purposeful nurturing. More specifically, we may analyze these stages as follows:

1. • Stage One: trying to establish a mode of cooperation, which would characterize Sino-Japanese relations in the ARF from 1994 to 2004 and the APT from 1997 to 2004;

2. • Stage Two: tolerating the other's schemes while deploying one's own stratagems to neutralize them, which describes their relationship in the ARF, APT, and EAS from 2005 to 2009;

3. • Stage Three: increasing attention to APT and EAS for diplomatic gains, by China and Japan; pro forma attendance in the ARF and ADMM+ by both countries reflects their security realignments in other set-ups beginning around 2007 but gathering strength since 2010.

The underlying tone of Sino-Japanese interactions in East Asian regional arrange-ments for at least a decade has been one of competition for influence over the sur-rounding countries constituting the member states of the forums.

In general, the functional effectiveness of a grouping tends to decrease as membership grows. Unsurprisingly then, to concentrate and maximize its own influence in the regional forums where it has the advantage, China would favor having fewer members in economic groupings such as the APT and EAS, while Japan would prefer the same in security groupings such as the ARF and ADMM+. A major consequence of this contest is that the “ASEAN Plus” arrangements have become a numbers game.

ASEAN REGIONAL FORUM: THE LIMITS OF INSTITUTING TRUST

First Stage: Attempts at Cooperation, 1994–2004

According to the ARF Concept Paper (1995), promotion of confidence-building measures (CBMs) constitutes the first stage of the forum's evolution, of which pressing for the transparency of a member state's military establishment should be the key undertaking.