US President Barack Obama's trip to Pakistan this year may be cancelled according to analysts in Washington, because of deteriorating relations between the two nations. The US President is now calling for the Pakistani government to honour the diplomatic immunity of an American man who shot and killed two men on a street in the city of Lahore.Consular employee Raymond Davis said he acted in self-defence during an armed robbery, though many Pakistani newspapers allege that he is actually a spy.President Obama has made a direct appeal for his release for the first time since Davis shot and killed the two Pakistanis on January 27 this year. US Secretary of State Hillary Clinton has already cancelled recent and future high-level talks and the diplomatic protests could go even higher.