Question: Which of the people with which S. K. Sikka played a crucial role was an Indian physicist who is best known for his role in India's nuclear program during its early stages?

<P0-S0> The 123 Agreement signed between the United States of America and the Republic of India is known as the U.S.–India Civil Nuclear Agreement or Indo-US nuclear deal. <P0-S1>  The framework for this agreement was a July 18, 2005, joint statement by then Indian Prime Minister Manmohan Singh and then U.S. President George W. Bush, under which India agreed to separate its civil and military nuclear facilities and to place all its civil nuclear facilities under International Atomic Energy Agency (IAEA) safeguards and, in exchange, the United States agreed to work toward "full" civil nuclear cooperation with India. <P0-S2>  This U.S.-India deal took more than three years to come to fruition as it had to go through several complex stages, including amendment of U.S. domestic law, especially the Atomic Energy Act of 1954, a civil-military nuclear "Separation Plan" in India, an India-IAEA safeguards (inspections) agreement and the grant of an exemption for India by the Nuclear Suppliers Group, an export-control cartel that had been formed mainly in response to India's first nuclear test in 1974. <P0-S3>  In its final shape, the deal places under permanent safeguards those nuclear facilities that India has identified as "civil" and permits broad civil nuclear cooperation, while excluding the transfer of "sensitive" equipment and technologies, including civil enrichment and reprocessing items even under IAEA safeguards. <P0-S4>  On August 18, 2008 the IAEA Board of Governors approved, and on February 2, 2009, India signed an India-specific safeguards agreement with the IAEA. <P0-S5>  After India brought this agreement into force, inspections began in a phased manner on the 35 civilian nuclear installations India has identified in its Separation Plan. <P0-S6> <ref name="INFCIRC/731"> </ref> The deal is seen as a watershed in U.S.-India relations and introduces a new aspect to international nonproliferation efforts. <P0-S7>  On August 1, 2008, the IAEA approved the safeguards agreement with India, after which the United States approached the Nuclear Suppliers Group] (NSG) to grant a waiver to India to commence civilian nuclear trade. <P0-S8>  The 48-nation NSG granted the waiver to India on September 6, 2008 allowing it to access civilian nuclear technology and fuel from other countries. <P0-S9>  The implementation of this waiver made India the only known country with nuclear weapons which is not a party to the Non-Proliferation Treaty (NPT) but is still allowed to carry out nuclear commerce with the rest of the world. <SEP> <P1-S0> Raja Ramanna "ರಾಜಾ ರಾಮಣ್ಣ" (Kannada) (28 January 1928 – 24 September 2004) was an Indian physicist who is best known for his role in India's nuclear program during its early stages. <SEP> <P2-S0> Waman Dattatreya Patwardhan (January 30, 1917 - July 27, 2007) was an Indian nuclear chemist, defence scientist and an expert in the science of Explosives engineering. <P2-S1>  He was the founder director of the Explosives Research and Development Laboratory (now known as the High Energy Materials Research Laboratory (HEMRL)) of India. <P2-S2>  He is considered one of the distinguished scientists in India due to his contributions to Indian space program, Indian nuclear program and missile program in their early stages. <P2-S3>  He developed the solid propellant for India's first space rocket launched at Thumba. <P2-S4>  He was responsible for developing the detonation system of India's first nuclear device which was successfully tested in 1974, an operation codenamed Smiling Buddha. <SEP> <P3-S0>  He is known to have played a crucial role, along with Raja Ramanna, Rajagopala Chidambaram and Basanti Dulal Nagchaudhuri, in the design and development of a Hydrogen Bomb by India, which was tested at the Pokhran Test Range in May 1998, under the code name, Operation Shakthi. <P3-S1> Satinder Kumar Sikka is an Indian nuclear condensed matter physicist, crystallographer and a former Scientific Secretary to the Principal Scientific Advisor of the Government of India. <P3-S2>  He was also involved in the Smiling Buddha tests, conducted in 1974. <P3-S3>  He was awarded the fourth highest civilian award of the Padma Shri, by the Government of India, in 1999.