The Pakistani premier's attendance will be a first in the history of the nuclear-armed rivals, which have fought three wars since independence in 1947.Pakistan has accepted an invitation to Prime Minister Nawaz Sharif to attend the inauguration of Indian Prime Minister-designate Narendra Modi, an official said on Saturday. "There will be a bilateral meeting on the sidelines between Prime Minister Nawaz Sharif and Mr. Modi," Mohyuddin Wani, the joint secretary of the Prime Minister's office, told Reuters. "Mr. Sharif will also be calling on the Indian president."The top source of friction is his aim to boost trade with India. Many army officers say India must vacate its part of the disputed territory of Kashmir before ties can improve. Ties have been particularly tense since the 2008 attacks on Mumbai blamed by India on Pakistan-based militants. Sharif came to power last year promising to rebuild relations with India but has been under pressure to toughen his stance from hardliners at home, particularly within the army.