Editing Nuclear weapon design (section)

===Fourth generation===
The idea of "4th-generation" nuclear weapons has been proposed as a possible successor to the examples of weapons designs listed above. These methods tend to revolve around using non-nuclear primaries to set off further fission or fusion reactions. For example, if [[antimatter]] were usable and controllable in macroscopic quantities, a reaction between a small amount of antimatter and an equivalent amount of matter could release energy comparable to a small fission weapon, and could in turn be used as the first stage of a very compact thermonuclear weapon. Extremely-powerful  lasers could also potentially be used this way, if they could be made powerful-enough, and compact-enough, to be viable as a weapon. Most of these ideas are versions of [[pure fusion weapon]]s, and share the common property that they involve hitherto unrealized technologies as their "primary" stages.<ref>{{cite arXiv |eprint=physics/0510071 |last1=Gsponer |first1=Andre |title=Fourth Generation Nuclear Weapons: Military effectiveness and collateral effects |year=2005}}</ref>

While many nations have invested significantly in [[inertial confinement fusion]] research programs, since the 1970s it has not been considered promising for direct weapons use, but rather as a tool for weapons- and energy-related research that can be used in the absence of full-scale nuclear testing. Whether any nations are aggressively pursuing "4th-generation" weapons is not clear. In many case (as with antimatter) the underlying technology is presently thought to be very far from being viable, and if it was viable would be a powerful weapon in and of itself, outside of a nuclear weapons context, and without providing any significant advantages above existing nuclear weapons designs<ref>[http://whyfiles.org/167new_nukes/4.html Never say "never"] {{webarchive |url=https://web.archive.org/web/20160418234450/http://whyfiles.org/167new_nukes/4.html |date=April 18, 2016}}. Whyfiles.org. Retrieved on 2011-05-01.</ref>