ISLAMABAD, Pakistan — With the opening of a treason trial looming over him this week, the former Pakistani military ruler Pervez Musharraf struck a defiant tone on Sunday, calling the case the worst kind of “political vendetta” and claiming that the country’s powerful military establishment was upset by his treatment.

In a rare interaction with reporters representing foreign news outlets, Mr. Musharraf spoke with a seeming confidence that belied a barrage of legal charges and harsh criticism in the press against him since his return from exile abroad in March.

In those early days, he presented himself as a potential savior for Pakistan’s political woes. But in the months since his return, as his political hopes imploded and as the new government of Prime Minister Nawaz Sharif, whom he deposed in a 1999 coup, began exploring charges against him, he has instead become a kind of public indicator of how much the country — and, perhaps, the military — might have changed since his time in power.

On Sunday, he insisted that he had been treated unfairly and suggested that the military was on edge over his fate, despite silence from Pakistan’s generals over the past few months.