Pakistan went into a state of 'high alert' last week after a threatening phone call made to President Asif Ali Zardari by someone from Delhi who posed himself as the Indian External Affairs Minister Pranab Mukherjee. Whether it was mere mischief or a sinister move by someone in the Indian external affairs ministry, or the call came from within Pakistan, remains unclear, and is still a matter of investigation. But several political, diplomatic and security sources have confirmed that for nearly 24 hours the incident continued to send jitters across the world. To some world leaders the probability of an accidental war appeared very high. It all started on November 28. Because of the heightened tension over the Mumbai carnage, some senior members of the presidential staff decided to bypass the standard procedures meant for such occasions, including verification of the caller and involvement of the diplomatic missions, and transferred the late-evening call to Mr Zardari. The caller introduced himself as Pranab Mukherjee and, while ignoring the conciliatory language of the president, directly threatened to take military action if Islamabad failed to immediately act against the supposed perpetrators of the Mumbai killings. As the telephone call ended, intense diplomatic and security activity started in Islamabad. Signals were sent to everyone who mattered about how the rapidly deteriorating situation may spiral out of control. Prime Minister Yousuf Raza Gilani was advised to immediately return to the capital from Lahore, and a special plane was sent to Delhi to bring back the visiting Foreign Minister Shah Mehmood Qureshi early in the morning on Nov 29 even when he was already booked to return by the same evening.