Force will have to be used if diplomacy fails.如果外交失败就只好诉诸武力了。

high-level diplomacy between the two embassies两个大使馆之间的高级别外交

They are still urging the President to step up his diplomacy and make a better case for war.他们仍在督促总统加强外交手腕, 为战争找到更好的理由。

He sometimes lacked diplomacy.他有时不够圆滑。

You will need to use a great deal of diplomacy.你将需要使用大量的交际手段。