At least 26 people were killed and 17 others wounded when gunmen opened fire on tourists in Indian-controlled Kashmir, the worst assault in years targeting civilians in a restive region that has seen an anti-India rebellion for more than three decades.

Tensions between arch rivals India and Pakistan were high on Thursday as New Delhi mounted a diplomatic offensive against Islamabad, blaming it for a deadly attack that killed 26 people, mostly tourists,

India announced a series of retaliatory actions, and hinted at the possibility of more, in response to what it called Pakistan’s support of terrorism on Indian soil.