  We consider N=1 supersymmetric quantum chromodynamics (SQCD) with the gauge
group U(N_c) and N_c+N quark flavors. N_c flavors are massless; the
corresponding squark fields develop (small) vacuum expectation values (VEVs) on
the Higgs branch. Extra N flavors are endowed with small (and equal) mass
terms. We study this theory through its Seiberg's dual: U(N) gauge theory with
N_c +N flavors of "dual quark" fields plus a gauge-singlet mesonic field M. The
original theory is referred to as "quark theory" while the dual one is termed
"monopole theory." The suggested mild deformation of Seiberg's procedure
changes the dynamical regime of the monopole theory from infrared free to
asymptotically free at large distances. We show that, upon condensation of the
"dual quarks," the dual theory supports non-Abelian flux tubes (strings).
Seiberg's duality is extended beyond purely massless states to include light
states on both sides. Being interpreted in terms of the quark theory, the
monopole-theory flux tubes are supposed to carry chromoelectric fields. The
string junctions -- confined monopole-theory monopoles -- can be viewed as
"constituent quarks" of the original quark theory. We interpret closed strings
as glueballs of the original quark theory. Moreover, there are string
configurations formed by two junctions connected by a pair of different
non-Abelian strings. These can be considered as constituent quark mesons of the
quark theory.
