Yes, you can.
http://www.fas.org/nuke/guide/usa/slbm/c-4.htm
Technically speaking, a missile and a jet fighter are aircrafts. But the greatest difference between the two vehicles lies in the degree of dependency on aerodynamic exploitation. The missile have the least dependency. The jet fighter have the greatest.
The jet fighter need aerodynamic exploitation for flight, specifically the right combination of thrust and lift through large expanse of lifting surfaces, aka wings and even the fuselage. Large flight control surfaces also facilitate rapid, abrupt, and unpredictable flight deviations, aka 'maneuvers'.
The missile relies largely on sheer thrust for flight with a minimum of aerodynamic exploitation for stability, specifically structural longitudinal stability. The longer the missile, the greater the tendency to flex -- lengthwise. The more powerful the thrust, the greater the compression on that same length, which compounds that tendency. But since the missile is not required to make radical and abrupt flight deviations, aka 'maneuvers', the way the jet fighter does, the highest demand for structural robustness is in the longitudinal axis.
So already we can see that the missile is a far less complex vehicle than the jet fighter in terms of structural engineering. The Agni-3's estimated weight is about 50 tons, but that is fuel-ed weight. No missile is deployed for combat readiness with no fuel, solid or liquid. What good is it? If the missile is solid fuel, then its specified weight includes the solid fuel.
For comparison, the F-111A's
EMPTY WEIGHT is 45 tons.
http://en.wikipedia.org/wiki/General_Dynamics_F-111_Aardvark
Look at the weight difference between fuel-ed and empty weight of the Saturn V...
http://en.wikipedia.org/wiki/Saturn_V
So if we take a defuel-ed the missile and disassemble it -- empty weight -- then absolutely with the right materials and new structural engineering knowledge we can have high empty weight reduction approaching the 50% range or more.
Here is the better deal...
Improved materials and structural engineering reduced empty weight but still retains the same fuel quantity capability. We now have, not only higher thrust-to-weight ratio, but also because of the lower empty weight, the same quantity of fuel now extends the range as well. We can swap some of that fuel load for more warheads, for example, and keep the original range.