  The black hole MAXI J1820+070 was discovered during its 2018 outburst and was
extensively monitored across the electromagnetic spectrum. Following the
detection of relativistic radio jets, we obtained four Chandra X-ray
observations taken between 2018 November and 2019 May, along with radio
observations conducted with the VLA and MeerKAT arrays. We report the discovery
of X-ray sources associated with the radio jets moving at relativistic
velocities with a possible deceleration at late times. The broadband spectra of
the jets are consistent with synchrotron radiation from particles accelerated
up to very high energies (>10 TeV) by shocks produced by the jets interacting
with the interstellar medium. The minimal internal energy estimated from the
X-ray observations for the jets is $\sim 10^{41}$ erg, significantly larger
than the energy calculated from the radio flare alone, suggesting most of the
energy is possibly not radiated at small scales but released through late-time
interactions.
