The United States is the most powerful country in the world, with a logistical system that is globe spanning and awe inspiring. It's something that would come in handy if you had to suddenly get supplies to tens of thousands, or even millions of people in an emergency.
Some of the worst relations Pakistan had with the US was when the government of Pakistan simultaneously became an openly nuclear state and supported the Taliban regime. That would be 1998 till September/October 2001. Drought overtook Pakistan in 1999, and it extended to Afghanistan as well. The first snows fell in November 2001 after three years of drought.
The drought ended simultaneously with the US invasion of Afghanistan. The Gods have a strange sense of humour.
And of course Pakistan's relation with the United States had improved.
In 2005, as the Afghan resistance re-erupted, the US began to look for culprits. Their relation with Pakistan began to deteriorate. And then an Earthquake happened in 2005.
And now, a three ship military task force is off the coast of Pakistan with US helicopters swarming all over the country. And just a month ago with the wikileaks expose, Pakistan and US relations were set to take a serious nose dive.
Strange world we live in.