Its boosters tout its massive economic promise and claim it could benefit the entire world and lift millions out of poverty.
But no one can say for sure what exactly the plan encompasses, and detractors warn it could be an expensive boondoggle at best or a massive expansion of Chinese imperial power at worst.
So what is One Belt, One Road?
No one is totally sure. At the most basic level, One Belt, One Road (OBOR) is a collection of interlinking trade deals and infrastructure projects throughout Eurasia and the Pacific, but the definition of what exactly qualifies as an OBOR project or which countries are even involved in the initiative is incredibly fuzzy.
"It means everything and it means nothing at the same time," said Christopher Balding, a professor of economics at Peking University.
Why is it so unclear?
While it might have originally had a comprehensible thesis behind it, OBOR has become such a popular buzzword that it's next to impossible to lock down criteria for how any given project would or could fit into the overall initiative.
Chinese officials tend to mention it regardless of what they're trying to promote, like a US lawmaker talking about "freedom."
Chenggang Xu, a professor of economics at the Cheung Kong Graduate School of Business, said it helps to think of OBOR as a "philosophy" or "party line," rather than anything concrete.