  For a Shimura variety of Hodge type with hyperspecial level at a prime $p$,
the Newton stratification on its special fiber at $p$ is a stratification
defined in terms of the isomorphism class of the Dieudonne module of
parameterized abelian varieties endowed with a certain fixed set of
Frobenius-invariant crystalline cycles ("$F$-isocrystal with
$G_{\mathbb{Q}_p}$-structure"). There has been a conjectural group-theoretic
description of the F-isocrystals that are expected to show up in the special
fiber. We confirm this conjecture by two different methods. More precisely, for
any $F$-isocrystal with $G_{\mathbb{Q}_p}$-structure that is expected to appear
(in a precise sense), first we construct a special point which has good
reduction and whose reduction has associated $F$-isocrystal equal to given one.
Secondly, we produce a Kottwtiz triple (with trivial Kottwitz invariant) with
the $F$-isocrystal component being the given one. According to a recent result
of Kisin which establishes the Langlands-Rapoport conjecture, such Kottwitz
triple arises from a point in the reduction.
