"It's a shame, we just heard about it," Trump said at the White House, after the Indian government said it had hit "terrorist camps" on its western neighbor's territory following a deadly attack on tourists in Indian-administered Kashmir.

"I guess people knew something was going to happen based on the past. They've been fighting for many, many decades and centuries, actually, if you really think about it," he added.

India and Pakistan have fought three full-scale wars since gaining independence from the British in 1947. Both claim Kashmir in full but administer separate portions of the disputed region.

"I just hope it ends very quickly," said Trump.

India had been widely expected to respond militarily since gunmen shot dead 26 people in Indian-administered Kashmir, mostly Hindus.

New Delhi has blamed militants that it has said were from Pakistan-based group Lashkar-e-Taiba, a UN-designated terrorist organization.

Pakistan's army said the Indian strikes targeted three sites in Pakistan-administered Kashmir and two in Punjab province, the country's most populous.

Islamabad said that three civilians, including a child, had been killed in Indian strikes.

The Indian strikes came just hours after the US State Department issued a fresh call for calm.

"We continue to urge Pakistan and India to work towards a responsible resolution that maintains long-term peace and regional stability in South Asia," State Department spokeswoman Tammy Bruce told reporters.

Her statement came after Indian Prime Minister Narendra Modi warned of stopping water from flowing across borders following the Kashmir attack.