The limiting factor is not the status of the aggressor power, but rather the status of the (potential) aligning powers. In the case of an Italian attack on Greece, the aligning major power has to be an active Allied major power at the time of the declaration of war.
19.2 Entering the war
A minor country enters the war when:
- a major power declares war on it (it joins the other side); or
- it aligns with a major power (see 9.8).
If a minor country aligns with a major power, it is controlled by that major power.
If an Axis major power declares war on a minor country on the American map, it may only align with the USA.
When Germany makes her compulsory declaration of war on Poland (see 9.3), it may only align with the Commonwealth.
In every other case, when one or more major powers declare war on a minor country, choose an active major power on the other side to align with it.
If there is more than one eligible major power, offer the minor to the major power whose capital city is closest to the minor’s capital (any home country in the case of the Commonwealth). If it declines, offer it to the next closest, and so on.
If every eligible major power declines, the minor (and all its controlled minors and territories) is immediately conquered by the attacking major power (see 13.7.1).




