Your perception about Nehru is wrong. He approached the UN with a view that it would force Pakistan to return the occupied land.it does't belong to them,who said to you
when pakistan invaded independent kashmir under hari singh,he asked indian help and signed to join with india but when india sent army after this annexation ,pakist has occupied till srinagar and we started to regain territory slowly and till kargil but our nehru went to un and stopped the war and loc came into use(line of actual control) nehru is one of the main reason for this whole problem as our army might have recovered whole kashmir,to avoid conflict it is de facto border not agreed one
But at the time USA and its Allies had a view that India a potential threat and and enemy status remained with USA. SO they favored Pakistan and brought in a cease fire and drew an official temporary line of control and put and end to Indian army's progression. If it wasn't for Nehru's quick actions, India wouldn't have even got a single piece of land in Kashmir.