If the Taliban and Al Qaeda were to take power in Afghanistan after American troops withdraw, it would lead to an Islamist takeover of Pakistan, a new book says.
Given the growing demand in the US to end its involvement in Afghanistan, American economic and military aid to Kabul may not last long after 2014, says the "Endgame in Afghanistan" (Sage).
Author Hiranmay Karlekar warns that if and when that happens, the embattled Hamid Karzai regime in Kabul might not even last as long as the Najibullah government did after the Soviet Union pulled out.
The consequent Taliban-Al Qaeda takeover "may then lead to an Islamist takeover of Pakistan's army and government", says the 353-page book, a comprehensive account of the Afghan conflict.
At the same time, Karlekar argues that Pakistan's present leadership, both civilian and military, "fully realize that they are in no position to dispense with American civilian and military aid.
"Equally, they do not want to destroy the Haqqani (militant) network and the Afghan Taliban which they consider to be their strategic assets..."
The books says the Pakistani state would also not desist from activities that undermine the American position and the Karzai government so as to install a pliant regime in Kabul.
"They are ... inheritors of a skill that their predecessors had turned into an art - taking Americans for a ride.
"They will, therefore, huff and pull on the brink but take care not to leap over."
But the situation in Pakistan would change if Islamists either take over or dominate the army, the author says.
While detailing the "deep-rooted radical tendency in Pakistan's security forces", the book says the possibility of a jehadi takeover of the army cannot be ruled out.
"The Pakistani army, however, is still a disciplined force," it says.
"By all indications, its top brass would not want to have an irreparable breach with the US.
"It is true that officers with liberal backgrounds and warm links with the West are getting increasingly fewer.
"But even the conservative ones may not want a sharp deterioration of ties with the US because that may mean a drastic curtailment, if not complete stoppage, of military aid, which has been considerable."