I think the most significant thing that's happening in terms of the Asian arms race is the growth of submarine capability, with a massive expansion on the part of the Chinese.
It's almost easier to list the countries that are not developing submarines than countries that are. They include new and unlikely players such as Bangladesh. You have a number of the southeast Asian countries deciding to double down on their own submarine capabilities, with Vietnam, for example, acquiring more submarines from Russia, and Malaysia, Thailand, Singapore, and Indonesia all either getting into the submarine business for the first time or renewing their fleets.
Then there are all of the things associated with submarines, including underwater drones and listening devices implanted in the seabed. The next war in the Asia-Pacific will be a war primarily around anti-submarine warfare, and the country that is best able to do that will be the winner.