Claiming that it had taken ‘‘forceful action’’ into allegations of the illegal transfer of nuclear parts, Pakistan on Tuesday said the country’s nuclear proliferation network no longer existed. ‘‘The chapter is closed,’’ Pakistan’s Foreign Office spokesperson Tasleem Aslam said, responding to Foreign Secretary Shyam Saran’s asking the International Atomic Energy Association to focus on Pakistan’s non-proliferation record. ‘‘The IAEA has already acknowledged and appreciated Pakistan’s cooperation.” She went on to say, ‘‘It is known to all that Pakistan is not to blame for nuclear proliferation in South Asia,’’ claiming that, after India’s nuclear tests, ‘‘Pakistan was obliged to respond to developments in the region.” PTI