In my opinion announcing that a new pact you've signed takes precedence over a NAP that you previously signed is tantamount to canceling the NAP. I wouldn't be happy about this.
However, it should be noted that prematurely canceling a NAP is less evil than breaking it with an actual sneak attack.
However, it should be noted that prematurely canceling a NAP is less evil than breaking it with an actual sneak attack.