The sparring between India and Pakistan last month threatened to spiral out of control and only interventions by U.S. officials headed off a bigger conflict, sources familiar with the events said.

Pakistan's foreign affairs minister has appeared to admit that his government is in contact with Jaish-e-Mohammed, which India alleges is harboured by Pakistan's intelligence agency.

Both countries have ordered air strikes over the last two days, the first time in history that two nuclear-armed powers have done so.