The US Government has done what it has never done against the Gambia Government. This is signifying a cooling down of relations. Quiet diplomacy to get governments to adhere to international standards is normal in international relations. Sanctions against countries, however, are done through the UN Security Council. Inter-state relation, however, is a question of reciprocity.
Countries could impose travel advice to their citizens so that they would not go to countries that seem to be unstable. It does impact on their tourism sector as well as the holding of conferences. They may send the envoy of a country back as retaliation for the expulsion of their own envoy by a given country. They may also issue visa ban and other minor sanctions to influence governments to open up to bilateral dialogue. As the Obama administration is coming to end, one should expect it to be polishing its record in combating human rights violations all over the world.
The EU parliamentary delegation has also mentioned their plan to recommend targeted sanctions if the Government fails to improve its human rights record.
No nation is an island. It is best to comply with international standards and expose those who violate them. Accusing others of being violators too is just the best way to attain moral authority to defend justice.