United States President Donald Trump on Friday said he had told Chinese President Xi Jinping that crushing the Hong Kong protesters would have “a tremendous negative impact” on efforts to reach an accord to end a 16-month trade war.

United States National Security Adviser Robert O’Brien said on Saturday that an initial trade agreement with China is still possible by the end of the year. He however warned Washington would not turn a blind eye to what happens in Hong Kong.

The comments add to growing worries that a Chinese crackdown on anti-government protests in Hong Kong could further complicate the efforts by the United States and China to end a prolonged trade war that has roiled global markets and undercut global economic growth forecasts.