From Jeff Foust's article in The Space Review:
The current round in the debate over property rights in space started with the publication last week of a white paper titled “Homesteading the Final Frontier”  by the Competitive Enterprise Institute (CEI), a non-profit think tank that promotes issues associated with free enterprise. In the white paper, CEI adjunct scholar Rand Simberg explained his approach to securing property rights beyond Earth.
Simberg agrees that the OST prohibits countries from claiming sovereignty over territory on the Moon or other bodies. However, “there’s maybe a loophole here,” he said a forum about his white paper held Thursday on Capitol Hill. “The idea is that recognition is not necessarily appropriation.”
Specifically, he suggests legislation whereby the US would recognize claims made by private entities, American and others, which meet certain conditions regarding habitation and transportation. While it would recognize those claims, he said, the US government would not attempt to defend those claims by force. “If that’s the case—it’s not an American entity, and it’s not going to be defended by the US government—how could that possibly be a claim of sovereignty?” Simberg asked.
In the white paper, Simberg offers a hypothetical example where, under such a system, the US would recognize a claim made by a company incorporated on the Isle of Man with investors from Dubai. “To say that such a recognition amounts to a ‘national appropriation’ by the U.S. of the legal real estate established with such a claim is plainly absurd,” he writes.