Washington: For Benazir Bhutto, the decision to return to Pakistan was sealed during a telephone call from Secretary of State Condoleezza Rice just a week before Bhutto flew home in October.

The call culminated more than a year of secret diplomacy - and came only when it became clear that the heir to Pakistan's most powerful political dynasty was the only one who could bail out Washington's key ally in the battle against terrorism.

It was a stunning turnaround for Bhutto, a former prime minister who was forced from power in 1996 amid corruption charges. She was suddenly visiting with top State Department officials, dining with UN Ambassador Zalmay Khalilzad and conferring with members of the National Security Council.

No threat

As President Pervez Musharraf's political future began to unravel this year, Bhutto became the only politician who might help keep him in power.

"The US came to understand that Bhutto was not a threat to stability but was instead the only possible way that we could guarantee stability and keep the presidency of Musharraf intact," said Mark Siegel, who lobbied for Bhutto in Washington and witnessed much of the behind-the-scenes diplomacy.

But the diplomacy that ended abruptly with Bhutto's assassination on Thursday was always an enormous gamble, according to current and former US policymakers, intelligence officials and outside analysts.

By entering into the legendary "Great Game" of South Asia, the United States also made its goals and allies more vulnerable - in a country where 70 per cent of the population looked unfavourably upon Washington.

Bhutto's assassination leaves Pakistan's future - and Musharraf's - in doubt, some experts said.