The Obama administration will not stop supporting Cuban human rights and democracy activists as part of any deal to restore embassies between the two countries, a top U.S. diplomat said Tuesday.

"I can't imagine that we would go to the next stage of our diplomatic relationship without an agreement" to see democracy activists, Assistant Secretary of State for Western Hemisphere Affairs Roberta Jacobson testified during a Senate Foreign Relations subcommittee hearing.

Her response came after vigorous questioning from Florida Republican Sen. Marco Rubio, chairing his first Senate hearing. Rubio read from an interview Josefina Vidal, Cuba's top negotiator, gave The Associated Press in which she tied the establishment of embassies to reduced U.S. support for Cuban dissidents.

Jacobson, the highest-level American official to visit Havana in several decades, said more talks on re-establishing full diplomatic relations are planned for later this month. Besides embassies, the talks focused on a range of concerns, from resolving fugitive and financial claims to managing immigration and more.

Lawmakers' response to the thaw in U.S.-Cuba relations has hardly fallen along traditional partisan lines. While Rubio voiced skepticism, Arizona GOP Sen. Jeff Flake is pushing to end U.S. travel restrictions to Cuba.

Among Democrats, California Sen. Barbara Boxer defended the Obama administration's move. But Sen. Bob Menendez of New Jersey, who is Cuban-American, argued the U.S. got a raw deal.

"Raul Castro is demanding the return of Guantanamo," Menendez complained. "A full list of U.S. concessions including compensations for the impact of the embargo, eliminating our democracy programs ... and he concedes nothing. So how much more are we willing to give? How much more are we willing to do to help the Castro regime fill the coffers of its military monopolies while the Cuban people still struggle to make ends meet?"

The two countries vowed to improve ties after a prisoner swap and the release of Alan Gross, an American aid contractor who had been held in Cuba for five years. The Obama administration has since relaxed several restrictions on Cuba under the American economic embargo and, as a sign of detente, Castro's government released 53 political prisoners.

Yet the Castros are not suddenly embracing democracy and freedom of speech. State Department human rights chief Tom Malinowski pointed to the roughly 140 short-term detentions in January as evidence the Castro regime has not changed.

The Cuban Commission for Human Rights and National Reconciliation, a dissident human rights organization, puts the number of political detentions in January at 178, noting it was the lowest monthly total in more than four years. In 2014, the group says the Cuban government carried out 8,899 short-term detentions. That's a monthly average of 741. Those numbers cannot be independently verified.

One potential source of optimism about the possibility of reform on the island involves telecommunications. Jacobson said some firms have already visited and "many more" are now interested. She suggested it's unclear how the Cuban government will respond.

Though lawmakers like Rubio caution that an open Cuba means more money "in the hands of the repressive Cuban military and its officials," Jacobson sees the risk differently.

"We strongly believe that the benefits of what the Cubans get in resources through this policy outweigh any benefit to the Cuban government that may be gained in a policy like this," she testified. "And those will be greater, we think, than what the Cuban government gains."

The hearing comes the same day Cuba published the first photos of Fidel Castro in five months. The 88-year-old former leader is seen speaking with a college student.

The next round of talks is expected to take place in Washington.

The Associated Press contributed to this report.