  Although the existence of dark matter has been widely acknowledged in the
cosmology community, it is as yet unknown in nature, despite decades of
research, which questions its very existence. This never-ending search for dark
matter leads to consider alternatives. Since increasing the enclosed mass is
the only way to explain the flat appearance of galaxies rotation curves in a
Newtonian framework, the MOND theory proposed to modify Newton's dynamics when
the acceleration is around or below a threshold value, a_0. Observed rotation
curves, generally flat at large distances, are then usually well reproduced by
MOND with a_0 ~ 1.2 10^{-10} m/s^2. However, the recent Gaia evidence of a
decline in the Milky Way rotation curve is a distinct behavior. Therefore, we
examine whether LCDM and MOND can accommodate the Gaia declining rotation curve
of the Milky Way. We first depict a standard model to describe the Milky Way's
baryonic components. Secondly, we show that a NFW model is able to fit the
decline, assuming a scale radius R_s of the order of 4 kpc. In a third step, we
show that the usual MOND paradigm is not able to reproduce the declining part
for a standard baryonic model. Finally, we examine whether the MOND theory can
accommodate the declining part of the rotation curve when relaxing the
characteristics of the baryonic components. To do so we use a MCMC method on
the characteristics of the stellar and the HI disk, including their mass. We
found that the stellar disk should be massive, of the order of 10^{11} M_\odot.
The HI disk mass is capped at nearly 1.8 10^{11} M_\odot but could also be
negligible. Finally, a_0 is consistent with 0, with an upper limit of 0.53
10^{-10} m/s^{2} (95\%), a value much lower than the above mentioned value
usually advocated to explain standard flat rotation curves in MOND theory.
