The Cuban flag was raised over Havana's embassy in Washington on Monday for the first time in 54 years as the United States and Cuba formally restored relations, opening a new chapter of engagement between the former Cold War foes, according to Reuters. Cuban Foreign Minister Bruno Rodriguez presided over the reinauguration of the embassy, a milestone in the diplomatic thaw that began with an announcement by U.S. President Barack Obama and Cuban President Raul Castro on Dec. 17. Serious differences remain between the United States and Communist-ruled Cuba, and efforts toward full normalization of ties are expected to proceed slowly. But the ceremonies carried enormous symbolism after more than two years of negotiations between governments that had long shunned each other. "The historic events we are living today will only make sense with the removal of the economic, commercial and financial blockade, which causes so much deprivation and damage to our people, the return of occupied territory in Guantanamo, and respect for the sovereignty of Cuba," Rodriguez said. The foreign minister spoke at a reception inside the stately building, which was visited by revolutionary leader Fidel Castro just months after he seized power in Cuba in 1959. He said the Cuban flag that hung outside the Washington embassy when it closed in 1961 will now be displayed inside. Earlier, a three-man honor guard marched onto the front lawn where the Cuban flag was mounted on a newly installed pole while a band played the Cuban national anthem. As the flag was slowly raised, there were competing chants from the crowd outside the gates. "Cuba si, embargo no!" Shouted one group. "Cuba si, Fidel no," yelled a much smaller group. In Havana, the U.S. Embassy was also reopened for business with no outward sign of change. Embassy staff flashed new badges and business cards, and the website, Twitter feed and Facebook page of the mission changed. The Stars and Stripes, however, will not be hoisted there until a visit by U.S. Secretary of State John Kerry expected on Aug. 14. More than 500 people, including Obama administration officials, U.S. lawmakers and a large visiting Cuban delegation, attended the ceremony at the nearly century-old mansion that was being converted back into the Cuban Embassy. The U.S. delegation was headed by Assistant Secretary of State Roberta Jacobson. Earlier and without fanfare, maintenance workers hung the Cuban flag in the lobby of the U.S. State Department, where it joined the banners of other countries with which the United States has diplomatic relations. In a further sign of a desire to move past decades of enmity, Kerry and Rodriguez, the first Cuban foreign minister on an official visit to Washington since the Cuban Revolution, were due to meet at the State Department and then hold a news conference later on Monday. The crowd at the embassy reopening included members of Congress who have supported rapprochement. "We've waited a long time for this day," Senator Patrick Leahy said as he entered the grounds. Asked if it was the end of a process, he said "it's just the beginning." No invitations went to hard-line anti-Castro lawmakers, such as Senators Marco Rubio and Bob Menendez, who have opposed Obama's outreach and modest easing of restrictions on business and travel. "You don't invite into your home those who want to do you harm," Gustavo Machin, deputy director for U.S. affairs in the Cuban Foreign Ministry, said in Havana last week. Republican presidential candidate Jeb Bush underscored his opposition to the diplomacy on Twitter on Monday: "Obama's rush to restore diplomatic relations with Cuba is wrong. This embassy will only serve to further legitimize repressive regime." The opening to Cuba marked a major application of Obama's presidential doctrine of negotiating with enemies, a concept that now faces an even tougher test with a nuclear deal reached with Iran last week. But both countries have made clear that restoration of ties, agreed on July 1, will be just a step in a long normalization process that is only inching along because of lingering disputes, as well as Havana's desire to keep a tight rein on Cuba's society and its state-run economy. Differences include the U.S. economic embargo, Cuba's human rights record and Washington's retention of its naval base at Guantanamo Bay. The embargo will remain in place, and only Congress can lift it, something majority Republicans are unlikely to do anytime soon.