Nuclear

In the mid-1970s, Pakistan took the uranium enrichment route to acquiring a nuclear weapons capability under the direction of A.Q. Khan. By the mid-1980s, Pakistan had a clandestine uranium enrichment facility, and Khan would later assert that the country had acquired the capability to assemble a first-generation nuclear device as early as 1984.[1] Islamabad conducted nuclear tests in May 1998 shortly after India, and declared itself a nuclear weapon state. Pakistan is not a signatory to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). It has also refused to ratify the Comprehensive Nuclear Test Ban Treaty (CTBT) and has blocked consensus at the Conference on Disarmament on starting negotiations for a Fissile Material Cutoff Treaty (FMCT).[2] According to 2011 estimates by the International Panel on Fissile Materials (IPFM), Pakistan has accumulated a stockpile of 2.75 ± 1 tons of highly enriched uranium (HEU) and 135 ± 45 kg of weapon-grade plutonium.[3] United States intelligence estimates in 2011 put the number of deployed weapons at around 90 to 110.[4]

Biological

Pakistan signed the Biological and Toxin Weapons Convention (BTWC) in April 1972 and ratified it in 1974.  While Pakistan is not known to possess biological weapons, it has talented biomedical and biochemical scientists and well-equipped laboratories, which would allow it to quickly establish a sophisticated biological warfare (BW) program should the government so desire.

Chemical

Pakistan signed the Chemical Weapons Convention (CWC) in 1993 and ratified the treaty in 1997. Islamabad has apparently made no admissions in its treaty-mandated declarations of having possessed chemical weapons. There is no substantiated evidence in publicly available literature that Pakistan has ever possessed chemical weapons.

Missile

Pakistan is developing both solid- and liquid-fueled ballistic missiles, based extensively on foreign systems including those from China and North Korea. Nuclear-capable ballistic missiles inducted by Pakistan into its defense services include the Ghaznavi (Hatf-3, range 400 km), Shaheen-I (Hatf-4, range 450 km), and the Ghauri (Hatf-5, range 1,200 km).[5] Missiles under development include the 2,000 km range Shaheen-II, which could be nearing operation, and the Nasr, a short-range missile tested in April 2011 with the ability to increase Pakistan’s deterrent “at all levels of the threat spectrum.”[6]  In addition to ballistic missiles, cruise missiles are increasingly part of Pakistan's nuclear delivery plans, including the ground-launched Babur (Hatf-7, range 600 km) and the air-launched Ra’ad (Hatf-8, range 350 km), which have each been tested several times.[7]

Sources:
[1] “Interview with Abdul Qadeer Khan,” The News (Islamabad), 30 May 1998, http://nuclearweaponarchive.org.
[2] "Pakistan Rules Out Test Ban Treaty Endorsement," Global Security Newswire, 19 June 2009, www.nti.org; and “Statement by Ambassador Zamir Akram, Permanent Representative of Pakistan at the Conference on Disarmamnet (CD),” Geneva, 27 August 2009, http://www.reachingcriticalwill.org.
[3] "Global Fissile Material Report 2011," International Panel on Fissile Materials, Sixth Annual Report, January 2012, www.fissilematerials.org.
[4] David E. Sanger and Eric Schmitt, "Pakistani Nuclear Arms Pose Challenges to U.S. Policy," The New York Times, 31 January 2011, www.nytimes.com.
[5] Hans M. Kristensen and Robert S. Norris, “Pakistan’s Nuclear Forces, 2011,” Bulletin of the Atomic Scientists, Vol. 67 No. 4, July/August 2011, http://bos.sagepub.com.
[6] “Press Release No PR94/2011-ISPR,” Inter Services Public Relations, 19 April 2011, http://www.ispr.gov.pk.
[7] Hans M. Kristensen and Robert S. Norris, “Pakistan’s Nuclear Forces, 2011,” Bulletin of the Atomic Scientists, Vol. 67 No. 4, July/August 2011, http://bos.sagepub.com.