SEOUL, South Korea's establishment of diplomatic relations with Cuba will likely deal a "blow" to North Korea, given the close brotherly ties Pyongyang and Havana have maintained for decades, a senior presidential official said Thursday. Years of secret negotiations and visits went into the formal establishment of bilateral diplomatic relations, which was sealed Wednesday by an exchange of diplomatic notes between the two countries' representatives to the United Nations in New York. The decision reduced to one the number of U.N. member states South Korea has yet to establish diplomatic ties with, namely Syria. "The establishment of South Korea-Cuba diplomatic relations was a long-cherished wish and task in South Korean diplomacy," the official told reporters. "It appears that it will be inevitable that North Korea will be dealt a considerable political and psychological blow." Cuba and North Korea described their relations as those of "brotherly solidarity" in a bilateral treaty signed on the occasion of then Cuban President Fidel Castro's visit to the North in March 1986. "The reason Cuba was unable to readily agree to diplomatic relations despite having positive feelings toward South Korea amid hallyu and other various circumstances was because of its relationship with North Korea," the official said, referring to the Korean Wave, or the global popularity of Korean pop culture. "This is the completion of our diplomacy vis-a-vis the socialist bloc that was friendly toward North Korea, including countries in Eastern Europe in the past," the official said, claiming the establishment of South Korea-Cuba diplomatic relations clearly shows where the tide is heading in history and to whom it is turning. Asked whether there was any communication between the two countries' leaders ahead of the announcement, the official said President Yoon Suk Yeol was briefed in detail on the latest developments as they happened but had no direct contact with his counterpart, Miguel Diaz-Canel, due to the absence of diplomatic r elations. The final agreement was reached over the recent Lunar New Year holiday and reported to the president by phone, the official said. The United States was also informed of the decision before the announcement. Source: Yonhap News Agency