  An integrable Kondo problem in the one-dimensional supersymmetric t-J model
is studied by means of the boundary supersymmetric quantum inverse scattering
method. The boundary $K$ matrices depending on the local moments of the
impurities are presented as a nontrivial realization of the graded reflection
equation algebras in a two-dimensional impurity Hilbert space. Further,the
model is solved by using the algebraic Bethe ansatz method and the Bethe ansatz
equations are obtained.
