What does “puncture veneer” mean? Is it a common idiom?

Solution 1:

It's headlinese, once you add all the articles and prepositions that would be in the normal version of that sentence you get: "The wiretapping claims that Trump made have punctured his veneer of Presidential civility".

In its literal definition "veneer" is:

A thin decorative covering of fine material (usually wood) applied to coarser wood or other material.

(M-W)

But it is often used in the metaphorical sense of:

An attractive appearance that covers or disguises true nature or feelings.

(Wiktionary)

And in that sense you will often see phrases like "puncture the veneer of XXX" or "see through the veneer of XXX" (though as Mari-Lou A points out, "puncture the veneer" itself seems to be a choice by the writer, not a common instance of that kind of phrase), which means seeing through that superficial appearance to the true nature underneath (or in this case, the true nature underneath being revealed as the "veneer" gets "punctured").

"puncture veneer" on its own isn't a phrase that exists (and googling it will mostly get you links to the articles you found anyway).

Solution 2:

No, 'puncture veneer' is not an idiom. Here 'puncture' is used as a verb and the meaning of 'veneer' is 'facade'. Thus the meaning of the entire headline, by assuming its literal meaning, is Trump's claims about wiretapping punctures the superficial presidential civility.