A satellite photograph obtained by ABC News reveals Pakistan is nearing completion of a third, previously unknown plutonium production reactor, suggesting Pakistan may be planning to expand its nuclear weapons arsenal. "With large stocks of plutonium, Pakistan can build a new generation of lighter, more powerful weapons that can more easily be launched via missiles and can cause far more damage," said David Albright, the president of the Institute for Science and International Security (ISIS), which, along with DigitalGlobe, provided the satellite image to ABC News. The image, taken on June 3, indicates the new reactor is a replica of a second heavy water reactor, also under construction, at Khushab, approximately 109 miles south of Islamabad, Pakistan’s capital. The third reactor is located a few hundred meters to the north of the second. The original reactor at the site began operations in 1998. According to Albright, construction of the third reactor has been especially rapid. In the GeoEye image from August 2006, only minimal ground excavation is visible. The Pakistani Embassy had no immediate comment. Pakistan’s facilities at Khushab are not subject to safeguard inspections by the International Atomic Energy Agency (IAEA). The existing reactor at Khushab is known to produce plutonium for Pakistan’s nuclear weapons program. Pakistan has not signed the nuclear Nonproliferation Treaty (NPT). It is one of only three states to opt out of the international treaty designed to promote cooperation in achieving nuclear disarmament and peaceful uses of nuclear energy. India and Israel are the other two. Experts estimate Pakistan has already built about 60 nuclear weapons. Until more is known about the power of these two new reactors, Albright says, it is difficult to estimate the number of weapons that could be built from plutonium harvested from the reactors’ spent fuel. With that caveat, he notes, the number of produced weapons could easily reach at least 10 each year. Do you have a tip for Brian Ross and the Investigative Team? This post has been updated.