Pakistan’s secret ISI unit ‘S1’ linked to decades of terror attacks against India: Report

Operating for more than 25 years, S1 has allegedly trained thousands of militants for infiltration and coordinated strikes inside India. (Representative image)

A covert unit within Pakistan’s Inter-Services Intelligence (ISI), codenamed “S1” or Subversion 1, has allegedly been the command centre for Islamabad’s cross-border terror operations targeting India for nearly three decades, according to Indian intelligence inputs.

Sources cited in an NDTV report have described S1 as the ISI’s most secretive and powerful terror operations wing, believed to have orchestrated or supported major attacks -- from the 1993 Mumbai serial blasts to the recent assault on tourists in Jammu and Kashmir’s Pahalgam early this April.

The unit reportedly operates under the direct control of a Colonel-rank Pakistan Army officer, aided by two senior officials known by their code names Gazi 1 and Gazi 2. Its base of operations is said to be located in Islamabad, and much of its funding allegedly comes from narcotics trafficking and illicit trade networks, it has been learnt from the report.

S1 operatives are said to be experts in bomb-making, handling small arms, and setting up improvised explosive devices (IEDs).

Intelligence reports suggest the unit maintains detailed maps of strategic Indian cities and security installations.

The unit has longstanding ties with major terror outfits, including Jaish-e-Mohammed (JeM), Lashkar-e-Taiba (LeT), and Hizbul Mujahideen. Sources claim that S1 trainers frequently visit militant camps in Pakistan and Pakistan-occupied Kashmir, often disguised with long beards and local clothing to blend in with recruits.

Operating for more than 25 years, S1 has allegedly trained thousands of militants for infiltration and coordinated strikes inside India. As per intelligence officials cited in the NDTV report, several terror groups remain unaware that their trainers are part of the ISI’s covert wing. This further displays the cell’s deep-rooted secrecy.

Meanwhile, in recent months, Indian security and intelligence agencies have intensified surveillance and financial tracking of suspected S1-linked networks. Investigators are focusing on tracing money flows and communications connected to Pakistan’s state-backed terror ecosystem, especially after the Pahalgam attack on April 22 which was followed by Operation Sindoor in May.