Question

求英语老师/高级翻译帮我看下两个句子动词的单复数对不对

Sentence 1:
大规模杀伤性武器及其运载工具的扩散，是对国际和平与安全的现实威胁.
My translation:
The proliferation of weapons of mass destruction and their means of delivery constitutes a threat to international peace and security
My interpretation:
我觉得这个句子简单来讲就是A和B的扩散，那么主语就是扩散这个动词，动词应该是三单形式加s。但也有联合国官方文件翻的是the proliferation of ... and their means...constitute a threat...我就有点搞不懂了。
Sentence 2：
国际防扩散机制权威性、普遍性和有效性]亟待增强。
My translation:
The authority, representation, and effectiveness of the international non-proliferation mechanism still need improving.
My interpretation:
我举得这个句子的简单来讲就是A、B、C需要加强，所以动词是复数。不知道这样的解读对不对，求翻译大师/英语教师帮我看下这两个动词的单复数形式对不对，谢谢！

Answer 1

The proliferation of weapons of mass destruction and their means of delivery is a real threat to international peace and security