Of Harvard’s Kennedy School of Government. Marshall wrote an op-ed in the July 5 Washington Post complaining about “weapons in space.” Not only was his timing poor — the article ran the day after North Korea launched, with “mixed success,” its latest test of the Taepodong II intercontinental ballistic missile — but pretending that space is not already a ground of military competition is no argument for a sensible American space policy. The real question is how to shape that competition in ways that protect the interests of the United States and its allies. Marshall is right to worry about ground-based anti-satellite weapons; but it’s nearly certain that China and others already possess such systems. Space is the international commons of the 21st century, as the open oceans have been the commons in the past. There will be a fight for space power; the question is how the United States deals with that fight.