A number of countries, including India, are looking at these new areas like pure fusion research which are not covered by the restrictions imposed by the CTBT.

More significantly, pure fusion research could undermine the present global nuclear order, which controls the spread of nuclear weapons by limiting access to materials such as highly enriched uranium and plutonium. The next generation nuclear weapons will not need these difficult-to-produce materials. Instead, the raw material for pure fusion weapons -- different isotopes of hydrogen -- are more easily available, for example from sea water.

As the pas de deux between Jaswant Singh and Strobe Talbott moves into a faster tempo this week, all the hand-wringing in India on the``conditional-unconditional'' signing of the CTBT may become a futile exercise as the game of nuclear weapons has already moved way beyond the ambit of the CTBT.

India may not be too far behind in the sphere of nuclear fusion research, according to top scientists here. ``India is not very far behind in nuclear fusion research from that in the West. A lot of people are working on the physics of fusion,'' former Atomic Energy Commission chairman P K Iyengar told The Indian Express.

A report by the US-based Institute for Energy and Environmental Research (IEER) made public last week accused the US and France of violating the CTBT by carrying out research on pure fusion weapons, for long the Holy Grail of nuclear designers all over the world.

Pure fusion weapons are hydrogen bombs with a difference. Until now thermonuclear weapons -- or hydrogen bombs as they are popularly known -- needed a fission device to trigger it by producing the high temperatures to begin a fusion reaction.

Now atomicscientists are examining a variety of other means, in particular high-powered lasers, that could become the match-stick to ignite the fusion fire.

The IEER report specifically mentions the National Ignition Facility, a huge laser complex coming up in Livermore, California, and the French facility Laser Mega Joule near Bordeaux, both working on using powerful lasers to induce thermonuclear explosions in the laboratory.

In simple words, the new research facilities use laser beams to shoot a sharp burst of energy onto a tiny pellet of hydrogen fuel, raising it to a white heat and causing the hydrogen atoms to fuse into helium in an explosion of pure fusion energy. The trick that the scientists are looking for is an efficient and compact mechanism to build deliverable pure fusion weapons.

The advantages or dangers, depending on the way you look at it, of pure fusion weapons are many. Doing away with the fission trigger makes the new generation weapons far more ``cleaner'' in terms of nuclear fall-out. Theycould be made extremely small, giving enormous flexibility for military planners.

The United States is pushing the frontiers of fusion research and is way ahead in the race to build next generation nukes. The other four nuclear weapons states are following suit, as are Germany and Japan, each having developed significant capabilities in fusion research.

The IEER report also makes a reference to half a dozen countries that have either laser or particle beam facilities that are partly devoted to the study of Inertial Confinement Fusion (ICF). ``In some cases, these facilities are fairly small such as the single beam facilities in India, South Korea and Israel,'' it said. The report also suggests that India and Israel may have used research done at these facilities in designing their nuclear weapons.

India is now expanding its fusion research infrastructure. An innocuous sentence in the Department of Atomic Energy's latest annual performance budget states that the Indore-based Centre for AdvancedTechnology (CAT) is developing a four-beam high-power laser.

India will have some catching up to do with the advanced countries on fusion research. ``There is a paucity of the kind of resources that would be required for such research,'' Iyengar said over the phone from Mumbai.

Analysts here say that instead of arguing about the CTBT, India should be putting real money and effort on fusion and other weapon research that is permitted by CTBT. Over the long term, mastery over pure fusion may be the password for entry to the new global game that is permitted by Comprehensive Test Ban Treaty.