China's Silk Road cuts through some of the world's riskiest countries

China has so far spent or committed more than $500 billion on the plan

Chinese President Xi Jinping’s new Silk Road to Europe traverses territory where most bond investors fear to tread.

Of the 68 nations China lists as partners in its Belt and Road Initiative, the sovereign debt of 27 are rated as junk, or below investment grade, by the top three international rating firms. Another 14, including Afghanistan, Iran and Syria, are either not rated or have withdrawn their requests for ratings.

President Xi’s vision, first proposed in 2013 and this week elevated to an official policy enshrined in the Communist Party’s constitution, involves spending as much as $1.2 trillion on railways, roads, ports