LONDON — A two-week standoff between China and Japan over a boat collision has once again underlined the communist state's penchant for bullying its neighbors, and might have done more harm than good for the emergence of China as the leader in the region over the long term.

As tensions mount in East Asia and Beijing makes it clear that it intends to defy international opinion to sell nuclear reactors to Pakistan, something seems to be changing in New Delhi too. India's prime minister, who has previously described China as India's greatest neighbor, is now suggesting that Beijing could be tempted to use India's "soft underbelly," Kashmir, and Pakistan "to keep India in low-level equilibrium."

Its ultra-cautious defense minister is now admitting that "there has been an increasing assertiveness on the part of China." After trying to push significant divergences with China under the carpet for years, Indian decision-makers are being forced to grudgingly acknowledge that the relationship with China is becoming increasingly contentious. The challenge now is to understand China and its motivations more clearly.