Trump, in a prime-time televised address to the nation, laid out his South Asia policy saying a "critical part" of it was to further develop US' strategic partnership with India.
He said after a "comprehensive review", it has been decided that the American strategy in Afghanistan and South Asia will change dramatically.
"A core pillar of our new strategy is a shift from a time-based approach to one based on conditions. I've said many times how counterproductive it is for the United States to announce in advance, the dates we intend to begin, or end, military operations," Trump said in his address.
Trump slammed Pakistan for its continued support to terrorist groups and warned Islamabad of consequences if it continues to do so.
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"We can no longer be silent about Pakistan's safe havens for terrorist organisations, the Taliban, and other groups that pose a threat to the region and beyond," Trump said.
"Pakistan has much to gain from partnering with our effort in Afghanistan. It has much to lose by continuing to harbour terrorists," he said, in a apparent warning to Pakistan.
India, the world's largest democracy, is a key security and economic partner of the United States, he said.
"We appreciate India's important contributions to stability in Afghanistan, but India makes billions of dollars in trade with the United States, and we want them to help us more with Afghanistan, especially in the area of economic assistance and development," Trump said.