It summoned the US ambassador Thursday to formally complain after an attack hit deep inside Pakistani territory.
This week's suspected US airstrike deep in Pakistani territory – part of an unpopular but escalating campaign – has put the new government here on increasingly wobbly footing.
In office for less than a year, it now faces one of the main challenges that forced former President Pervez Musharraf from office in August: appearing to accept US conditions in the "war on terror" against the wishes of its people.
While the government led by President Asif Ali Zardari doesn't face the disruptive opposition that brought down Mr. Musharraf's regime, it's increasingly on the defensive, especially after The Washington Post reported Sunday that it tacitly agreed to the attacks in September.
On Thursday, Islamabad summoned US Ambassador Anne Patterson to protest the previous day's airstrike – not the first time it's formally complained to US officials. Yet the attacks have persisted: Pakistan has seen at least 20 strikes in the past three months, including a rare ground incursion in September.
"If this pattern continues," says Hassan Askari Rizvi, a political analyst and former professor of Pakistan studies at Columbia University, "the Pakistani government will be looking at some seriously tough times ahead."