请解释 美国 421条款

The Section 421 safeguard process

Section 421 allows the US president to restrict Chinese products that are "being imported into the United States in such increased quantities or under such conditions as to cause or threaten to cause market disruption" to the competing US industry. Market disruption exists when imports of Chinese goods are "increasing rapidly...so as to be a significant cause of material injury, or threat of material injury, to the domestic industry."

这是美国贸易法案第421章“防卫”的主要内容。
第421章允许美国总统在中国产品“大量进口美国或在某种条件下对与之竞争的美国产业造成破坏或威胁破坏市场”时，可以采取限制中国产品的措施。当中国商品的进口“快速上升...从而对美国国内产业造成了显著的实际伤害，或有产生实际伤害的威胁”时，就存在市场破坏情况。

这个条款怎么这么热呀好多人来问。。。