America’s threat to deny her oil and metals, against a guarantee of good behaviour as Washington should judge it, was therefore tantamount to strangulation.

1. 句子主干：America’s threat （主语）was （系动词）therefore tantamount to strangulation. （表语）   therefore，副词作状语。

因此，美国的威胁无异于扼杀。

2. to deny her oil and metals：不定式是 threat 的第一个定语。

3. against a guarantee of good behaviour as Washington should judge it：介词短语是 threat 的第二个定语。在该介词短语中含有一个 as 引导的比较分句（划线部分）

，作 a guarantee of good behaviour 后置修饰语（或定语）。

所以说，这个介词短语，既不是插入语，也不是前置。