The fourth round of diplomatic talks between the US and Cuba in Washington DC ended without an announcement on opening embassies in their respective countries, officials said. However, the officials said they were able to make "significant progress" on restoring diplomatic ties during the two day session.

According to Voice of America, the latest talks focused on the issues involving the reopening of embassies after diplomatic ties were severed more than 50 years ago.

US Assistant Secretary of State for Western Hemisphere Affairs Roberta Jacobson, who co-led the talks, said: "I do remain an optimist, but I am also a realist about 54 years that we have to overcome."

Jacobson added that the two countries still had a "few things that need to be ironed out" and were working quickly to resolve them.

Her Cuban counterpart, the general director of Cuba's US division in the Ministry of Foreign Affairs Josefina Vidal Ferreiro, said the two parties agreed to continue discussing key issues, according to Voice of America. "Both delegations agreed to continue the exchange on aspects related to the functioning of diplomatic missions," Vidal said.

Diplomatic access still a sticking point

One of those key issues could be diplomatic access, Jacobson said during a briefing on 22 May. "There are various circumstances in which embassies operate in somewhat restrictive environments," she said.

"We have confidence that when we get to an agreement, our embassy will be able to function so that our officers will be able to do their jobs."

Another important issue is that of restrictions on US diplomats travelling around Cuba. "The Cubans have said they are willing to allow that [unimpeded travel] but only if US diplomats will refrain from providing support to Cuba dissidents. So, that's been a sticking point," William LeoGrande, a Latin American politics professor at American University, told Voice of America.

According to Jacobson, a fifth round of diplomatic talks may not be needed to resolve those issues. On 20 May, the Cuban diplomats surpassed a major hurdle in the talks by gaining access to banking services in the US.

The two countries have been mending their severed diplomatic ties after a historic meeting between US President Barack Obama and Cuba President Raul Castro in December. The two presidents announced on 17 December that the countries would restore full diplomatic ties.