This paper is devoted to study the non-Archimedean locally convex
spaces

having the following property: For all non-Archimedean
locally convex spaces

, every compact operator

has an extension to a compact operator

. The
results obtained depend strongly on the spherical completeness of
the ground field. On the other hand, the situation here is
completely different from its Archimedean counterpart. Our results
also lead to some new characterizations of spherically complete
fields and of discretely valued fields.