Lawlessness is rife in Pakistan's north-western regions
By Jonathan Beale
BBC News, Washington
"Pakistan's pants are on fire!"
This may be a strange way to describe the state of a country, but it was the metaphor used by one US congressman.
It was not meant as some kind of playground taunt, but to describe the widespread alarm at recent developments, with extremists fanning the flames.
In the White House the words may be more measured, but the sentiment is the same.
US Secretary of State Hillary Clinton recently accused the Pakistani government of "abdicating" its responsibility by signing a peace deal with Islamist militants in the Swat valley.
Pakistan, along with Afghanistan, presents President Barack Obama with his greatest immediate foreign-policy challenge.
It is as serious a problem as Iraq was for George Bush.
This is how senior Obama administration officials have described Pakistan in recent days: "a mortal threat", "a direct threat to US National Security", "a military top priority".
So what is Mr Obama's strategy to deal with this growing crisis?
Mr Obama wants Mr Karzai and Mr Zardari to start trusting each other
The first is to look at Pakistan and Afghanistan together. There is even a word for it - "AfPak".
Success in Afghanistan is now seen as dependent on stability in Pakistan, and vice versa. Hence the president's decision to invite both leaders to the White House.
There has been a serious debate in Washington as to whether Presidents Hamid Karzai and Asif Ali Zadari can be trusted.
Both men have been accused of accommodating extremists and of failing to tackle corruption.
But despite genuine misgivings, Mr Obama realises he cannot be seen to be meddling in another nation's affairs.
That would only backfire and feed strong anti-US sentiment.
So he is going to make the most of the hand that has been dealt.
That means investing in both Mr Karzai and Mr Zadari's future. He wants the two men to begin trusting each other too.
Blame and mutual suspicion have undermined co-operation in the past.
But Mr Obama wants Mr Karzai and Mr Zadari to begin working closely together.
And this joint meeting in the White House will not be a one-off.
The Obama administration wants to see regular tete-a-tetes. AfPak officials will be encouraged to share intelligence, to co-operate in policing their shared border and to improve trade links.
It is not just a matter of trust. Mr Obama is backing up this strategy with thousands of additional US soldiers and billions of dollars.
He has already ordered an extra 17,000 troops to Afghanistan and 4,000 military trainers.
The White House insists this is not a military surge. The emphasis is also on improving governance and everyday life in both countries.
The US wants to counter the influence and appeal of the Taleban and its supporters.
Washington clearly has more leverage in Kabul than Islamabad.
In Pakistan, it must tread more carefully. There is no talk of sending American troops into the country.
Instead this administration will offer to train Pakistan's counter-terrorism forces.
Congress has been asked to provide $1.5bn (£1bn) of aid to Pakistan for the next five years.
There will be conditions attached. Washington is putting pressure on Islamabad to refocus its military from one border to another - from India to Afghanistan.
And the CIA and its predator drones will still be keeping a beady electronic eye and a hellfire missile pointed at the extremists.
The greatest fear is that Pakistan's nuclear weapons will fall into the wrong hands.