Hidden Arrows Are Difficult to Guard - 暗箭难防

暗(an)箭(jian)难(nan)防(fang)

"暗": "secretly,furtively"
"箭": "arrow,discharge an arrow from a bow"
"难": "with difficult,hard"
"防": "deal with ,pervent"

The literal translation of this idiom is "Hidden arrows are difficult to guard."

Corresponding English idiom:" to Back stab." or "do/say something Behind someones back"

Example sentence: Mr Putin also relies on such better-the-devil-you-know thinking. (普京也是依靠这种"明枪易躲, 暗箭难防"式的思考方式.)