NEW : A first source says Pakistani were aware of heightened activity , but did not pinpoint it to Osama bin Laden . Pakistan knew about the intelligence activity in the city Abbottabad , first source says . Pakistani officials did not suspect the uptick in activity was tied to Abbottabad , first source says . The relationship between Pakistan and Abbottabad is increasingly strained .
NEW : A second source says Pakistanis were aware of heightened activity , but did not pinpoint it to Abbottabad . Pakistan knew about the intelligence activity in the city Abbottabad , first source says . Pakistani officials did not suspect the uptick in activity was tied to Osama bin Laden , first source says . The relationship between Pakistan and the United States is increasingly strained .