Although Portugal and the United Kingdom have good relations, Spain so far is not without allies either. Italy needs little discussion; the relationship between Spain and Italy has improved a lot since Carlo came to power, and the two have signed defensive alliances based on cooperation treaties.
The cooperation between Austria-Hungary and Spain was something King Luis hadn't foreseen. Initially, King Luis planned to select a suitable princess from the Portuguese Royal Family to marry Carlo, ensuring that Spain would not be hostile towards Portugal through marriage ties.
But Carlo clearly had a better choice; an ally like Austria-Hungary is far stronger than Portugal as an ally.
With the help of Austria-Hungary, could Spain defeat Portugal, assisted by the British? This question hardly requires thought; the answer is that Spain could easily defeat Portugal.
