The piracies of the Moros endanger the islands, and allow the Dutch to hope for alliance with them against the Spaniards; and the importance of the islands to Spain is urged forcibly.
A letter addressed by Los Rios Coronel to the king (probably in 1620) urges that prompt aid be sent to Filipinas for its defense against the Dutch and English who threaten its coasts.

To it he adds an outline "treatise on the navigation of Filipinas," which sustains his demand by forcible arguments.

The rich Oriental trade amounts to five millions of pesos a year, which mainly goes to sustain the Dutch and their allies, the enemies of Spain, whose commerce they will utterly destroy unless some check is placed on their audacity; and the effectual method of doing this is to deprive them of that trade.

An armed expedition for the relief of the islands is being prepared by the king; it should be despatched via the Cape of Good Hope, and all possible efforts should be made to drive out the Dutch and English from the Eastern seas.

Los Rios proposes that for this purpose loans be asked from wealthy persons in Nueva Espana and Peru; and that the vessels needed be built in India.