Security around parliament has been tightened
Pakistan's parliament is meeting for a rare briefing by the military on the security situation.
The Senate and the National Assembly will be told why the efforts to contain Islamic militancy have failed so far.
The meeting will also try to establish a national consensus on how to counter the Taleban.
Attacks targeting Pakistani leaders have increased as the army continues operations against Taleban militants in tribal regions near the Afghan border.
The meeting is being described as "in-camera" which means it is not open to the public or the press.
On Wednesday the former director general of military operations and the chief of Pakistan's intelligence service (ISI), Lt-Gen Ahmad Shuja Pasha, conducted the briefing. It will be followed by a question-and-answer session on Thursday.
Prime Minister Yousuf Raza Gilani is expected to deliver a summing-up speech at the end.
More than 15 politicians, who are not MPs, have also been invited to attend.
These include Pakistan Muslim League (N) chief, Nawaz Sharif, and a number of political leaders who boycotted the national elections held in February.
Last month's attack on the Marriott has increased security fears
Massive security arrangements have been made around the parliament house which has been declared a "red zone".
All roads leading to the parliament building have been blocked and the police are checking all vehicles heading towards the house.
It is not clear how long the session will last.
Some political parties have suggested it should continue for two to three days, given the importance of the matter and the amount of information the parliamentarians would like to receive, process and discuss.
The parliamentarians are expected to seek information on a wide range of issues pertaining to the proliferation of militancy in the country despite the heavy military deployment in the Federally Administered Tribal Areas (Fata) since 2002.
Questions are also expected on the sources of Taleban funds and arms.
Although the insurgents apparently have access to huge amounts of both, it still remains unexplained as to how they get them.
Pakistan has seen many deadly attacks by militants in recent months.
Former prime minister and leader of the Pakistan People's Party, Benazir Bhutto, was assassinated in December last year.
An attack on the Marriott Hotel in Islamabad last month killed and wounded dozens of people.
Last week, the residence of the Awami National Party leader, Asfandyar Wali, was attacked in Charsadda.
This will be only the third in-camera session in Pakistan's parliamentary history and the first in which the military is likely to share secrets pertaining to national security with public representatives.
The first in-camera session in 1974 led to a law declaring the Ahmadi community as non-Muslim.
The second in 1988 paved the way for the signing of the Geneva Accord, which brought to an end the Soviet occupation of Afghanistan.