r.;ldcr^oround siros and the strengthenirrg o" inr.rconLinenral derivcry vehjcles, theintrocuction of nucleat submarine forces ."'ith nis s ife-launcting capalltity (iorceshitherto considered virtualry invul-nerabte because of trreir mobility andinvisibility), the repfacement of liquid fuel by sotid fue1., and maintenance ofsome vulnerable forces like bo{bers on alerts, are arr factors which to s.meextent can be said to have hefped to stabirlze deterrence. rt is generaflybelieved that the nore invulnerable the forces) the less tenptation for a std.te torisk a first strike because it vour-d in any event be the target of intolerablereprisals. rmprovement s in the accuracy of missires, however, call intc questionthe invu1nerability of stationary strategic r^reapons, since their protection cannotwithstand the effects of a very c.Iose nuclear explosion" The emei6lence ofprecision veapons to be used against hard targeLs has thus r-aised bhe possibilic,yof a counter-force strategy and has given inpetus to nerr doctrinal deverop*enr,s. 301 . tf ICBt4s in their sil,os cannot be made inrrulncrabre ty virtue of hardening,defence or sheer numbers against a threat of destruction and if the rcBM force isdeemed vital by a nation as part of its sbrategic offensive force, it seemspossible that the united states and the ussR courd place their rcBlt forces in alaunch-on-attack status. This would, however, not be a very stable situation.The disadvantages of a launch-under-att ack systen 1ie in the possibility ofaccidental , mistaken faunch, and. in the new vulnerabifities rhich such a systernnight bring. Sti11 one of the super-powers, in the belief that it is to bevanquished in the sLrategic arms comnetition, mighL inplement I aunch-unde r-attack ,as best it can. Even though this night reduce the provocation to initiate anucfear exchange, the introduction of such a new el-ement of instabil-itv in thebalance r^rould. be a matter of serious concern. 302. One aspect of the technological devetopment which should not be overfookedis the effect of increasingly sophisticated technology on the clarity 01.distinctions between varicus doctrinal concepts. Distinctions betveen oererrence,var-fighting, conventional, nuclear, strategic, theatre and tactical ar.e al1becoming very diffuse through the development of various weapon technologies. Theblurring of these distinctions may have de-Leterious effects on the possibifitiesof defining a particul-ar nuclear threshold, although the political. andpsychological- aspects of it are probably nore important than the technolosicalaspect. 303. Besides the technological deveropment there are natural-ly afso other r.orcesthat, influence the fornati on of various doctrines, srrch a.s f,o_titical and militaryenvironment, historical experienees and traditionar views, psychological factorsand even environrnental considerations. D. Nuclear doctrines of the nuclear_\"reapon States
**Analysis**
The text appears to be discussing the development and implications of nuclear weapons and strategies, highlighting the importance of technological advancements, doctrine, and deterrence. It also touches on the potential consequences of a launch-on-attack system and the blurring of distinctions between various doctrinal concepts.

**Category**
Science and technology, International relations