  Recent measurements of the cosmic microwave background (CMB) anisotropies by
BOOMERANG and MAXIMA collaborations have tightened the observational
constraints on theories of structure formation. They disagree with the
predictions of conventional topological defect models. Considering the fact
that topological defects are predicted by the majority of realistic particle
physics models, the exact nature of the constraints imposed by the recent data
on the population and the properties of the defects must be fully understood.
We show that the predictions of current cosmic string models can be brought
into a closer agreement with the observations by choosing a closed universe
with $\Omega=1.3$ and by including the effects of the small-scale structure and
radiation products of the strings. These alone, however, are not sufficient for
obtaining a good fit to the measured shape of the angular power spectrum. To
fit the data cosmic strings would either have to be correlated on large
(perhaps superhorizon) scales or would have to possess a higher degree of
coherence, i.e. be more ``time-correlated'.
