  In recent years there have appeared in the literature a large number of
static, spherically symmetric metrics, which are regular at the origin,
asymptotically flat, and have both an event and a Cauchy horizon for certain
range of the parameters. They have been interpreted as regular black hole (BH)
spacetimes, and their physical source attributed to electric or magnetic
monopoles in a suitable chosen nonlinear electrodynamics. Here we show that
these metrics can also be interpreted as exact solutions of the Einstein
equations coupled to ordinary linear electromagnetism{\textemdash}i.e., as
sources of the Reissner-Nordstr\"om (RN) spacetime{\textemdash}provided the
components of the effective energy-momentum tensor satisfy the dominant energy
condition (DEC). We use some well-known regular BH metrics to construct
nonsingular RN black holes, where the singularity at the RN center is replaced
by a regular perfect fluid charged sphere (whose charge-to-mass ratio is not
greater than $1$) which is inside the RN inner horizon.

General Relativity and Quantum Cosmology