Which tool might be used to limit imports from cuba but maintain exports to cuba

Sanctions

Explanation:

Sanctions are often seen as a preliminary measure from governments to restrain a certain country who has not aligned to international treaties or has had diplomatic tensions with them. These do not include leaving a complete treaty without effect but rather aiming at a certain part of that treaty, like restricting imports from a certain country until diplomatic relations normalize. This, however, does not affect exporting businesses, as they are able to regularly send their products to that particular country unless that particular country decides it will also block imports.

Arkansas, Missouri, Iowa, Oklahoma, Kansas, and Nebraska, North Dakota and South Dakota, Montana, Wyoming, and Colorado,  Texas, New Mexico