Islamabad has drawn the 'red line'. It ably took the 'pressure' from the United States on the Mumbai attacks, and is seen as adopting a 'principled position': India must provide evidence; Pakistan cannot hand over to India any of its nationals; no foreign agencies will be allowed to interrogate Pakistani nationals on its soil.
Alongside, Islamabad launched its own 'initiatives': a joint investigative mechanism and a high-level team to travel to Delhi. Islamabad says Delhi's green signal is awaited. Indeed, it promptly acted on the United Nations Security Council call, which was what India demanded as per US advice.