WASHINGTON (Reuters) - The United States could impose additional penalties on four unidentified countries that do not cooperate with requests to return their citizens, a Department of Homeland Security (DHS) spokesman said Wednesday. The State Department and the DHS can sanction countries that do not cooperate with removals, but has only used that punishment authority twice in the past 15 years. The current 12 countries deemed recalcitrant are China, Cuba, Vietnam, Laos, Iran, Cambodia, Myanmar, Morocco, Hong Kong, South Sudan, Guinea and Eritrea. Acting DHS Secretary Elaine Duke sent a letter to the State Department last week identifying the latest four countries that could face the new penalties. DHS spokesman David Lapan declined to discuss possible sanctions or the names of the four countries that could face additional sanctions, including denying visas. However, CNN cited a DHS official close to discussions about the deliberations as saying on Wednesday the four under consideration were Cambodia, Eritrea, Guinea and Sierra Leone. In two cases since 2000, the United States halted issuing visas to government officials and their families to Guinea and Gambia. Lapan said in some cases the DHS has no choice but to release some convicted criminals who served prison time but could not be returned to their home country because their home country refuses to cooperate. “We have tens of thousands of individuals,” Lapan said.  The DHS identifies countries that can be sanctioned and the State Department decides what, if any, sanctions could be imposed. The DHS has said that it has final deportation orders against 35,000 Cuban citizens that have criminal histories that Cuba refuses to accept. 