It's important that Japan and Asean jointly express some kind of political message on freedom of over-flight and navigation on high seas," said Ichiro Fujisaki, a professor at Sophia University in Tokyo and a former Japanese ambassador to the United States.
"If Japanese and Asean leaders fail to touch on the issue it will encourage expansionist factions inside China to take more aggressive actions," he said.
The special summit is being held to mark the 40th anniversary of relations between Japan and Asean, but it comes at a time when Japan is reemgaging with the region after several years in which it has been muscled out by China's growing economic might.
It also comes weeks after China's declaration of an Air Defence Identification Zone over a tranche of the East China Sea, including islands disputed with Japan, a move that ratcheted up an already-tense dispute.
Beijing said planes entering the zone must obey its orders and provide a flight plan to Chinese authorities, or face unspecified "defensive emergency measures".
Analysts say China's strategy with Asean has been to split off countries and negotiate with them on an individual basis. The United States and its allies would like the grouping to present a united front.