Just to be really clear, it's not my job to start drawing red lines for other countries. Canada states its position very clearly that we believe very strongly in and support the international humanitarian law and the law of armed conflict. That very clearly prohibits attacks on nuclear facilities. We've made that position very clear for exactly the purposes that you outline.
Evidence of meeting #119 for National Defence in the 44th Parliament, 1st session. (The original version is on Parliament’s site, as are the minutes.) The winning word was significant.
A video is available from Parliament.