VIVEK Y. KELKAR, MUMBAI Pakistan is tottering. Its collapse could spark a conflagration that spills well beyond its immediate neighbors...As Pakistan spirals into a deep economic crisis, its government has collapsed, replaced by a motley and improbable coalition of parties that have nothing in common and are highly unlikely to cooperate for the country’s benefit. The army continues to call the shots, but religious radicals openly call for jihad against the centrist political establishment. If Pakistan were isolated and unarmed, the world could safely ignore this. But it isn’t. Pakistan is not only armed but nuclear-armed—and as Americans learned to their sorrow in Afghanistan, what happens in Pakistan doesn’t stay in Pakistan...China has been fondly envisioning a trade zone spanning Afghanistan, Pakistan Iran, and Central Asia, right down to the Caspian Sea. China needs Pakistan to achieve regional hegemony, isolate India, and exclude the US from Asia. The CPEC is crucial to the web that China is spinning across Asia.