Washington: Islamabad's expansion of its nuclear arsenal aimed at India amidst continued instability in Pakistan has raised fears of a radical takeover or diversion of nuclear material and technology, according to a US Congressional report. While US and Pakistani officials continue to express confidence in controls over Pakistan's nuclear weapons, continued instability in the country could impact these safeguards, the independent Congressional Research Service said in a new report. Islamabad is reported to have taken a number of steps to improve its nuclear security and to prevent further proliferation of nuclear-related technologies and materials since the 2004 revelations about a procurement network run by notorious Pakistani scientist A. Q. Khan, it noted. "However, instability in Pakistan has called the extent and durability of these reforms into question," said the CRS report on Pakistan's Nuclear Weapons for US lawmakers. "Some observers fear radical takeover of the Pakistani government or diversion of material or technology by personnel within Pakistan's nuclear complex," it said. "Furthermore, continued Indian and Pakistani nuclear weapons development could jeopardize strategic stability between the two countries," the report said. "Pakistan's nuclear arsenal probably consists of approximately 110-130 nuclear warheads, although it could have more," CRS said. Islamabad is also producing fissile material, adding to related production facilities, deploying additional nuclear weapons, and new types of delivery vehicles, said the report based on published material. Pakistan's nuclear arsenal is widely regarded as designed to dissuade India from taking military action against Pakistan, the CRS report noted. Islamabad has also undertaken an expansion of its nuclear arsenal and development of new types of nuclear weapons as also adopted a doctrine called "full spectrum deterrence." This has "led some observers to express concern about an increased risk of nuclear conflict between Pakistan and India, which also continues to expand its nuclear arsenal," it said. According to one unofficial estimate cited by CRS, Pakistan has produced approximately 3,000 kilograms of weapons-grade HEU and approximately 200 kilograms of plutonium for nuclear weapons. Islamabad continues to produce both HEU and plutonium for nuclear weapons and is developing and deploying a variety of weapons, it said. Pakistan has tested a version of the Shaheen-1 missile, called the Shaheen-1A, with a range of 900 kilometres, the report said Additionally, Islamabad has announced flight tests of a nuclear-capable ballistic missile, called the Shaheen-3, with a range of 2,750 kilometers. This missile is designed to reach Indian islands so that India cannot use them as "strategic bases" to establish a "second strike capability", the CRS report said citing retired Lt Gen Khalid Ahmed Kidwai, former Director General of Pakistan's Strategic Plans Division, Some observers have expressed concern that non-strategic nuclear weapons could increase the risk of nuclear conflict between India and Pakistan, the report said. "Despite Islamabad's stated wish to avoid a nuclear arms race with New Delhi, Pakistan appears to be increasing its fissile production capability and improving its delivery vehicles in order to hedge against possible increases in India's nuclear arsenal and also to deter Indian conventional military action," the report said.