The death of Jyotindra Nath Dixit, India's National Security Adviser, at a time when talks with two of her neighbours Pakistan and China are at a historical juncture and poised for a breakthrough, is a huge blow.

J.N. 'Mani' Dixit was 68.

The pipe-smoking former diplomat, who died of a massive heart attack in a New Delhi hospital at 6am yesterday, brought a rare synergy to every interaction. It characterised his embrace of the media that turned to him for clarity, with his colleagues who revered him and his counterparts in foreign capitals, who developed a healthy respect for their adversary.

At a Dubai hotel in 1991, he firmly brushed aside murmurs from his ambassador to give an interview to Gulf News that put India's much criticised support for Saddam Hussain in the First Gulf War in perspective.

He has done the same, over and over through the years. No wonder then, that India's finest foreign policy boffin, recalled after retiring from service ten years ago, and the author of seven definitive books on foreign policy, is deeply mourned.

"He was the finest foreign secretary we ever had," said Indian diplomats in the region. Many said they were "honoured" to serve with him, and had lost their voice in the Prime Minister's Office.

An irreplaceable father figure, mentor and guide to a generation of men and women with whom he relished the cut and thrust of debate, he was the logical choice as NSA (National Security Adviser) when the Congress party which he joined in 2003, unexpectedly won power last year.

Not only did he grow into the role as the country's key behind-the-scenes negotiator, he was the indisputable architect of India's foreign policy under Prime Minister Manmohan Singh.

The current foreign minister, who is there because of his loyalty to the Gandhi clan, is woefully inadequate.

First, as the Cold War ended and India grappled with the challenge of dealing with the United States in a unipolar world, and again, this last year when a visionary foreign policy initiative became imperative, it was Dixit who scripted Delhi's new role.

As India's ambassador to Pakistan, Afghanistan, Sri Lanka and Bangladesh at momentous times in their evolution, he was uniquely positioned to tackle and win over the countries that viewed Delhi's rising profile with suspicion.

One of the key breakthroughs, largely unnoticed in the India-Pakistan clamour is Myanmar, whose pro-Chinese generals set aside India's support for jailed opposition leader Aung San Suu Kyi and agreed to stop insurgents from seeking refuge in their territory. He is an expert on Iran, and was key to India's pragmatic interaction with Israel.

The decision to send relief to Sri Lanka and other South East Asian nations despite reeling from the recent tsunami, was Dixit's over-arching vision of India as a regional power coming into play. A vision that he spelt out at the Zayed Centre in Abu Dhabi in 2003, weeks after he had joined the Congress party as foreign policy adviser.

Reviled as "Viceroy" when he served as India's ambassador to Sri Lanka, it was on his advice that India sent troops to fight the separatist Tigers.

The no-nonsense diplomat was also the first ambassador to Bangladesh, where his rapport with Shaikh Mujibur Rahman, that country's founding father, was legendary; as in Afghanistan, where too, he was India's first ambassador.

His abiding legacy is, however, as the nation's pointman for peace initiatives with rival Pakistan. India's Track One talks with Pakistan, personally handled by Dixit, could suffer a body blow. He had a reputation for being a hawk. But Dixit's meetings with Pakistan President General Pervez Musharraf's National Security Adviser Tariq Aziz, including a meeting in Dubai, were marked by realism rather than the muddled nostalgia for the past that marked his predecessor's.

His death leaves unfinished business. Ties between India and China, who fought a border war in 1962, have been warming in recent years. In July last year, Dixit and Chinese Executive Vice-Foreign Minister Dai Bingguo led the talks to demarcate the 3,500-km border, an issue that has lingered for more than four decades.

But the peace process with Pakistan has stagnated in recent months. It would be wise on Manmohan Singh's part to press for a foreign minister who is a lot more astute than Natwar Singh.

While no one can really fill Dixit's shoes, Singh is reportedly looking at either expanding the role of M.K. Narayanan, his adviser on internal security, or calling for the services of Ronan Sen, India's current ambassador to the United States, or former foreign secretary Salman Haider.

Diplomats in the region have said retired diplomat Satindra Lambah, too, could be a worthy successor to the Dixit legacy.

In his cavernous rooms at the Prime Minister's Office, the workaholic's list of appointments on the eve of a crucial visit by Pakistan's Prime Minister Shaukat Aziz, showed a veritable who's who had passed through his doors.

All greeted I am sure, with that wonderful twinkle in his eye and his signature double handed clasp.

Dixit, who is survived by his wife Anu, and six children, will be an extremely hard act to follow.