Labour leader Helen Clark says a secret recording of Bill English shows that if there is a war going, National wants to be a part of it.
On Tuesday 4 November, TV3 broadcast a tape of comments the National deputy leader made at a cocktail function during the party's annual conference in August.
In it, Mr English says he is a bit worried about US presidential candidate Barack Obama because there is a limited effectiveness in being moralistic about international relations.
He goes on to say there still needs to be someone who is willing to pull the trigger.
Miss Clark says the comments show National is militaristic, and would commit New Zealand to wars that have no just basis.
She says Labour has no knowledge of who is behind the secret taping.
National's leader John Key has dismissed the tape as a dirty campaign trick by Labour.