By Patricia Zengerle and Lesley Wroughton WASHINGTON (Reuters) – Political detentions have declined in Cuba since the Dec. 17 U.S.-Cuban rapprochement but it is unclear if this is a trend, a U.S. human rights official told a congressional hearing on Tuesday. “The nature of the Cuban regime has not changed and we have not claimed so,” Assistant Secretary of State Tom Malinowski told U.S. lawmakers’ first hearing on Cuba since President Barack Obama and Cuban President Raul Castro said they would seek to normalize relations. Malinowski said roughly 140 political opponents had been temporarily detained by the Havana government in January. We’re going to be watching this very carefully.” The Cuban Commission on Human Rights and National Reconciliation said on Monday Cuban police detained 178 opponents of the Castro regime in January, the lowest monthly total in more than four years.