An attack on tourists in India's Himalayan territory of Kashmir this week sparked a new crisis between nuclear armed South Asian neighbours India and Pakistan, with New Delhi blaming militants with "cross-border linkages" for the killings.

Pakistan's threat to suspend key treaties with India, including the Simla Agreement, raises concerns over military and diplomatic relations.

Relations between India and Pakistan are cratering following a deadly militant attack in Indian-administered Kashmir that has sparked tit-for-tat reprisals and raised fears of another military escalation between the nuclear-armed rivals.