1. He said President Biden told the Ukrainian leader that the United States will stand up firmly for Ukraine's sovereignty and territorial integrity.
stand up for 支持;捍卫;坚决维护
Don't be afraid to stand up for yourself.
要敢于维护自己的权利
。2. U.S. law enforcement officials say they have hit back at the Russian-based criminal network that caused gas pipelines to shut down across parts of the country last month.
hit back 反击
The President has hit back at those who have criticised his economic reforms
总统对那些批评过其经济改革措施的人进行了反击
。