As was shown in the inadvertent release of the email, there was some concern about breaking existing agreements, and there was concern about commitments that had been publicly made. Five Eyes chiefs of defence had decided that this kind of winter warfare training—and it was winter survival training rather than warfare training—was probably not the best use of our allied time, and we thought it was possibly a risk to continue with that training. Therefore, it was a difference of opinion amongst professionals that was resolved with the cancellation of the training.
On April 12th, 2021. See this statement in context.