President Monroe's First Address to Congress

James Monroe by Samuel Morse
from the wikipedia

Even before George Graham arrived in Galveston, President James Monroe had already decided that Jean Laffite should be asked to leave. As early as December of 1817, he said so in his first address to Congress. After describing the Amelia Island Incident, which culminated in the capture of that independent island by an American naval force, President Madison went on to say this:

A similar establishment was made at an earlier period by persons of the same description in the Gulf of Mexico at a place called Galvezton, within the limits of the United States, as we contend, under the cession of Louisiana. This enterprise has been marked in a more signal manner by all the objectionable circumstances which characterized the other, and more particularly by the equipment of privateers which have annoyed our commerce, and by smuggling. These establishments, if ever sanctioned by any authority whatever, which is not believed, have abused their trust and forfeited all claim to consideration. A just regard for the rights and interests of the United States required that they should be suppressed, and orders have been accordingly issued to that effect. The imperious considerations which produced this measure will be explained to the parties whom it may in any degree concern.

  To obtain correct information on every subject in which the United States are interested; to inspire just sentiments in all persons in authority, on either side, of our friendly disposition so far as it may comport with an impartial neutrality, and to secure proper respect to our commerce in every port and from every flag, it has been thought proper to send a ship of war with three distinguished citizens along the southern coast with these purpose. With the existing authorities, with those in the possession of and exercising the sovereignty, must the communication be held; from them alone can redress for past injuries committed by persons acting under them be obtained; by them alone can the commission of the like in future be prevented.

President Monroe's use of the term "impartial neutrality" belies his assertion that he has the right to "suppress" the establishment at Galveston, when Galveston is outside the territorial claims of the United States at that time. His questioning of whether these establishments were ever "sanctioned by any authority whatever" begs the question by what authority the government of any country, and especially an upstart like the United States,  is sanctioned.

To conquer a territory outside your own borders requires a declaration of war against those who hold it. To tell an established government that it must be suppressed is an act of war. You would think that if this is what James Monroe had in mind, he would be asking Congress for a declaration of war against the currently established government at Galveston. Instead, he informs Congress that he has sent a ship of war.

Jean Laffite had a policy engraved in stone not to make war on the United States, whom he regarded as his ally. But the United States more than once made war on him, without a declaration.