Indian troops secured Jammu, Srinagar and the valley itself during the First Kashmir War, but the intense fighting flagged with the onset of winter, which made much of the state impassable. Prime Minister Nehru, recognising the degree of international attention brought to bear on the dispute, declared a ceasefire and sought UN arbitration, arguing that India would otherwise have to invade Pakistan itself, in view of its failure to stop the tribal incursions. The plebiscite was never held, and on 26 January 1950, the Constitution of India came into force in Kashmir, but with special provisions made for the state. India did not, however, secure administrative control over all of Kashmir. The northern and western portions of Kashmir came under Pakistan's control in 1947, and are today Pakistan-administered Kashmir. In the 1962 Sino-Indian War, China occupied Aksai Chin, the north-eastern region bordering Ladakh, which it continues to control and administer.