  Large High Energy Physics (HEP) experiments adopted a distributed computing
model more than a decade ago. WLCG, the global computing infrastructure for
LHC, in partnership with the US Open Science Grid, has achieved data management
at the many-hundred-Petabyte scale, and provides access to the entire community
in a manner that is largely transparent to the end users. The main computing
challenge of the next decade for the LHC experiments is presented by the HL-LHC
program. Other large HEP experiments, such as DUNE and Belle II, have
large-scale computing needs and afford opportunities for collaboration on the
same timescale. Many of the computing facilities supporting HEP experiments are
shared and face common challenges, and the same is true for software libraries
and services. The LHC experiments and their WLCG- partners, DUNE and Belle II,
are now collaborating to evolve the computing infrastructure and services for
their future needs, facilitated by the WLCG organization, OSG, the HEP Software
Foundation and development projects such as HEP-CCE, IRIS-HEP and SWIFT-HEP. In
this paper we outline the strategy by which the international HEP computing
infrastructure, software and services should evolve through the collaboration
of large and smaller scale HEP experiments, while respecting the specific needs
of each community. We also highlight how the same infrastructure would be a
benefit for other sciences, sharing similar needs with HEP. This proposal is in
line with the OSG/WLCG strategy for addressing computing for HL-LHC and is
aligned with European and other international strategies in computing for large
scale science. The European Strategy for Particle Physics in 2020 agreed to the
principles laid out above, in its final report.
