respect to future movement. The influence of
considerations with respect to time (in addition to those noted above
with regard to space) is also a factor whose importance increases when
urgency is a matter of immediate concern.

With regard to feasibility, the technical capabilities and
limitations of the armed forces (page 67) are, of course, among the
principal factors. These capabilities and limitations are respectively
promoted and imposed primarily by considerations peculiar to the
particular medium of movement involved.

With specific regard to the areas within which military operations may
suitably be undertaken, the fundamental distinctions created by
recognized political sovereignty require attention. That part of the
surface of the earth which comprises its land area is recognized as
the property or the charge of one or another of the sovereign states,
although in certain cases the title may be in dispute. The air above a
nation's territorial domain is generally understood to be part of that
domain. The point to be observed is that there are no land areas which
belong equally to all nations. Accordingly; because of the factor of
neutral sovereignty, both land and air forces of belligerent States
may be under the necessity of following indirect routes to their
physical objectives.

In the case of the sea, however, all those portions of the earth's
surface which are covered by water (exclusive only of the recognized
territorial waters of the several nations), i.e., the high seas, are
presumably common property. The same applies to the air above the sea.

These considerations, and the fact that the surface of the sea is a
broad plane, permit open sea areas to be traversed by a variety of
routes to an extent not applicable in the case of land areas and the
air above them. In addition, the fact that technological developments
have been such as to permit movement, not only on the surface of the
sea and through the air above but also beneath the surface, gives
distinctive characteristics to the sea when considered as a theater of
operations.

The surface of the sea has, from the earliest days to the present,
provided roads over which human beings in greatest numbers and the
resources of the world in greatest weight and volume can be
transported in single carriers. From the standpoint of any belligerent
it is imperative that, during war, these roads be kept open to the
extent demanded by the needs of the State.