  We review the ALPHA collaboration strategy for obtaining the QCD coupling at
high scale. In the three-flavor effective theory it avoids the use of
perturbation theory at $\alpha > 0.2$ and at the same time has the physical
scales small compared to the cutoff $1/a$ in all stages of the computation. The
result $\Lambda_\overline{MS}^{(3)}=332(14)$~MeV is translated to
$\alpha_\overline{MS}(m_Z)=0.1179(10)(2)$ by use of (high order) perturbative
relations between the effective theory couplings at the charm and beauty quark
"thresholds". The error of this perturbative step is discussed and estimated as
$0.0002$.
