Any country under pressure is liable to break agreements, interfere, or ignore selected rules. The pressure doesn't have to be trade-related.
I cannot emphasize enough that the US is probably not more untrustworthy than it historically has been; all of this stems from Trump. It's prudent to assume that relations will normalize after Trump is gone (probably a lot sooner once Americans start feeling the self-imposed damage) and act accordingly with long-term interests in view. Follow the trend line, not the outlier.