Mons, Belgium — NATO Commander Bernard W. Rogers feels more secure now than he did four months ago, before NATO's controversial Euromissile deployments began. His reasons, as described in an interview at his headquarters, are based squarely on deterrence rather than ''war fighting.'' He sees the value of NATO nuclear weapons as deterring Soviet nuclear use rather than offsetting Western conventional weakness once hostilities have broken out.
The latter role has been a primary one for theater nuclear weapons ever since NATO adopted its ''flexible response'' guidelines (''flexible'' between conventional and nuclear weapons) in 1967 - at a time when the West had clear superiority in theater nuclear weapons.
NATO policy still calls for a resort to nuclear weapons if they are needed to prevent defeat; and General Rogers stressed he wants to maintain this option, not give it up in a ''no first use'' pledge as advocated by former Defense Secretary Robert McNamara and others.
The option is too important, he suggested, in adding uncertainty to Soviet planning, compelling the Warsaw Pact to disperse any conventional attack force (to avoid setting up vulnerable nuclear targets) - and thus deterring conventional as well as nuclear war.
Given the present state of NATO's conventional defense, he would have to request nuclear release ''fairly quickly'' in war, General Rogers said. But in practice, he implied, NATO would at this point be worse off after introduction of nuclear weapons, since ''there is a balance against us in theater nuclear weapons and in strategic weapons'' and ''the Soviet Union knows, if she used theater nuclear weapons with the imbalance against us, she can devastate us more than we can her.''
Soviet forward stationing in Eastern Europe of the SS-21 (which has been replacing the Frog), SS-22 (in deployment outside Soviet territory for the first time), and SS-23 (which will replace the Scud) does not require changes in his planning, Rogers said. The Soviets have been publicizing these deployments as retaliation for the new NATO Euromissiles without acknowledging they have had nuclear systems in Eastern Europe for years.
The Soviet Union would in any case - in a change from earlier Soviet planning - probably not begin any attack on Western Europe with nuclear weapons, Rogers says, but would keep the initial thrust conventional.
On the issue of NATO's shorter-range nuclear weapons, Rogers would not commit himself to any estimate of the numbers he considers essential. NATO's Nuclear Planning Group preempted Rogers's anticipated recommendation for a reduction in numbers by getting last year's NATO defense ministers' meeting in Montebello, Quebec, to cut NATO's total 6,000 nuclear warheads in Europe by a net 1,400 (a smaller cut than the Europeans would have liked).
Rogers did imply strongly that his own several-year nuclear study - which will be completed by April 1985 - would endorse continued deployment of nuclear artillery. The US Army has been keen on keeping this weapon available for battlefield use, while Europeans have tended to regard it as too short-range a weapon, one that could box defending armies into using it or losing it.
On a related issue, Rogers discounted West German fears that the US Army's 1982 doctrine of AirLand Battle, with its emphasis on preparation for nuclear war-fighting, might slide the American NATO force toward something approaching automatic use of nuclear weapons in any battlefield situation.
In rebuttal, Rogers stressed the military has no predelegated authority for first use of nuclear weapons and that government authorization at the political level would have to precede the initial and every subsequent use of nuclear weapons as long as the Warsaw Pact had not used them.
On AirLand Battle as a whole, Rogers clearly dissociated his NATO command from the US Army's concept of potential preemptive action and of deep offensive ground operations behind enemy lines in wartime. The West Germans in particular have been anxious lest planning for such operations lead European public opinion to think NATO was no longer a purely defensive alliance.
''I don't want to imply any criticism of the US Army. It needs to have something out in front of it,'' Rogers said. It has a ''concept for use worldwide.'' But ''if we're going to fight in Western Europe, we're going to fight as a coalition. We're going to fight under our doctrine, our concept of operations, and not under that of any individual nation.''
Rogers would authorize counterattacks behind enemy lines only to regain any NATO territory lost to a Warsaw Pact attack, he said, and then only to a depth of 25 to 30 kilometers (15 to 19 miles) ''at the max.''