Why? I don't see the connection between the US training troops in African countries and China's infrastructure plan unless you're saying the infrastructure plan should be opposed militarily if necessary.
Of course, "related to" and "justifies" are not synonyms.
But I agree that this stands on its own as a topic and Belt and Road would feel shoehorned in within an article this short.
What connection? That both are trying to gain more influence in Africa? Is the journalistic connection also obvious with something like the Gates Foundation, which is also trying to gain more influence in Africa?
It's hard to see how the US's more divisive approach can beat China's more inclusive one. I assume the reasons for this, as mentioned above, tie into the different setups, America with a huge military/industrial complex and China with a much better infrastructure track record (e.g. compare the high speed rail networks in both countries).
Gross simplifications obviously, but maybe the argument still holds?
Disclaimer, not read the WSJ article due to paywall.