搜了一下网络，网友的这句话不太全面。涉及到一些东西，网友这样处理，值得赞。我把整句话贴过来：

And the policy he is keenest on, tariffs, has been a failure, netting a flimsy agreement from China to buy more farm goods (which Mr Bolton says the president asked Mr Putin to do to help him win re-election).

我个人认为这是共用介词 on 的缘故：The policy on tariffs that/which he is keenest on has been failure. 这种现象具体怎么称谓，我真不知道。希望对你的问题能有所帮助。