“纸上谈兵”用英语怎么说？

"纸上谈兵" 是指理论上，一个单词就行了“theoretical" 或其副词 " Theoretically"
eg:
These are indeed real projects, not theoretical ones.

我在越狱里面看到的是
junk talk

to fight only on paper
to be an armchair strategist
to engage in idle theorizing

be an armchair strategist
engage in idle theorizing

be an armchair strategist
engage in idle theorizing

Paper