Whilst it is not my purpose to recommend the adoption of any measure with a view to the acquisition of the “dominion and sovereignty” over Yucatan, yet, according to our established policy, we could not consent to a transfer of this “dominion and sovereignty” either to Spain, Great Britain, or any other European power.  In the language of President Monroe in his message of December, 1823—­

  We should consider any attempt on their part to extend their system to
  any portion of this hemisphere as dangerous to our peace and safety.

In my annual message of December, 1845, I declared that—­

Near a quarter of a century ago the principle was distinctly announced to the world, in the annual message of one of my predecessors, that “the American continents, by the free and independent condition which they have assumed and maintain, are henceforth not to be considered as subjects for future colonization by any European powers.”  This principle will apply with greatly increased force should any European power attempt to establish any new colony in North America.  In the existing circumstances of the world, the present is deemed a proper occasion to reiterate and reaffirm the principle avowed by Mr. Monroe, and to state my cordial concurrence in its wisdom and sound policy.  The reassertion of this principle, especially in reference to North America, is at this day but the promulgation of a policy which no European power should cherish the disposition to resist.  Existing rights of every European nation should be respected, but it is due alike to our safety and our interests that the efficient protection of our laws should be extended over our whole territorial limits, and that it should be distinctly announced to the world as our settled policy that no future European colony or dominion shall with our consent be planted or established on any part of the North American continent.

Our own security requires that the established policy thus announced should guide our conduct, and this applies with great force to the peninsula of Yucatan.  It is situate in the Gulf of Mexico, on the North American continent, and, from its vicinity to Cuba, to the capes of Florida, to New Orleans, and, indeed, to our whole southwestern coast, it would be dangerous to our peace and security if it should become a colony of any European nation.

We have now authentic information that if the aid asked from the United States be not granted such aid will probably be obtained from some European power, which may hereafter assert a claim to “dominion and sovereignty” over Yucatan.