"Washington is planning to designate the Iranian Islamic Revolutionary Guard Corps (IRGC) as a terrorist group, the Wall Street Journal reported on April 5, citing unnamed U.S officials.
According to the officials, the decision will be officially announced by the U.S. State Department as early as April 8. This will be first time Washington to formally designate another country’s military a “terrorist group.”
The President Donald Trump administration reportedly hopes that this decision will increase pressure on Tehran. However, some U.S. officials believe that this step could endanger U.S. troops deployed near IRGC forces in the Middle East." WSJ and SF
The AUMF on terrorism has been used far and wide as a hunting license to attack any armed group that could even distantly be thought a terrorist enemy. The anti-terrorism AUMF makes such attacks legal under US law.
The official designation as "terrorist" of the IRGC which is a 125000 man army with its own navy and air force makes it legal for the US Armed Forces to attack the IRGC and its people wherever they are found and under any circumstances that may occur. It is a declaration of war.
The neocon nitwits (Pompeo, Bolton, Hannah, etc.) may think that Iran's reaction to this declaration of war will be submission to their will but IMO that is very unlikely. IMO it is more likely that the IRGC will absorb the new reality and will prepare for war with the US.