Pakistan, attempting to force the issue of Kashmir's accession, cut off supplies and transport links. Its transport links with India were tenuous and flooded during the rainy season. Thus Kashmir's only links with the two dominions was by air. Rumours about atrocities against the Muslim population of Poonch by the Maharajah's forces circulated in Pakistan. Shortly thereafter, Pathan tribesmen from the North-West Frontier Province of Pakistan crossed the border and entered Kashmir. The invaders made rapid progress towards Srinagar. The Maharaja of Kashmir wrote to India, asking for military assistance. India required the signing of an Instrument of Accession and setting up an interim government headed by Sheikh Abdullah in return. The Maharaja complied, but Nehru declared that it would have to be confirmed by a plebiscite, although there was no legal requirement to seek such confirmation.