Clinton is visiting with officials in New Delhi this week. The focus of her meetings ranged from bilateral security issues to clean and renewable energy.
She called on Asian countries to work together to "create a new Silk Road" of transnational networks of economic and transit connections.
"That means building more rail lines, highways, energy infrastructure, like the proposed (natural gas) pipeline to run from Turkmenistan, through Afghanistan, through Pakistan into India," Clinton said.
Turkmenistan aims to deliver natural gas through Afghanistan, Pakistan and India from its vast domestic reserves. The project is seen as a rival to plans from Iran through its so-called Peace Pipeline.
Security of the Turkmenistan-Afghanistan-Pakistan-India pipeline route through Afghanistan is an impediment, though the Afghan government made several pledges to relieve those concerns.
TAPI is favored by Western powers over the Iran's pipeline project because of diplomatic concerns with dealing with Iran.