MIAMI — President-elect Donald Trump threatened on Monday to reverse President Barack Obama’s diplomatic opening toward Cuba if the island’s communist regime fails to agree to terms for a “better deal.”

Putting pressure on the Cuban government, Trump pledged to “terminate” Obama’s historic policy without more Cuban concessions, a position the president-elect took as a candidate that has received renewed attention three days after Fidel Castro’s death.

“If Cuba is unwilling to make a better deal for the Cuban people, the Cuban/American people and the U.S. as a whole, I will terminate deal,” Trump posted on Twitter, his preferred medium of communication in the weeks following his election.

His tweet came a day after top transition advisers signaled Trump intends to keep the hardline position on Cuba he adopted late in his presidential campaign. The message to Cuba: Do more to reciprocate, or pay the price when the White House is under new management beginning Jan. 20.

“Clearly, Cuba is a very complex topic, and the president-elect is aware of the nuances and complexities regarding the challenges that the island and the Cuban people face,” Trump spokesman Jason Miller told reporters Monday.

He declined to say how much of a priority Cuba will be for the new administration, given Castro’s death.

“This has been an important issue, and it will continue to be one,” Miller said. “Our priorities are the release of political prisoners, return of fugitives from American law, and also political and religious freedoms for all Cubans living in oppression.”

Later at the White House, Obama Press Secretary Josh Earnest said dismantling the policies of the last two years is “just not as simple as one tweet might make it seem.”

“There are large companies in the United States, cruise operators and hotel operators, that have invested significant sums of money in investing in infrastructure and doing other work to do business down in Cuba,” Earnest said. “So, unrolling all of that is much more complicated than just the stroke of a pen.”

On Monday, the first scheduled commercial flight departed from Miami and landed in Havana. There will soon be 110 such daily flights from the U.S. to Cuba, according to the White House.

Earnest also defended Obama’s statement from Saturday offering condolences to the Cuban people over Castro’s death — a sentiment that was not accompanied by any condemnation of Castro’s brutality. That’s because Obama is focused on the future, Earnest said.

Castro, he added, was “a towering figure who had a profound impact on the history of not just his country, but the Western Hemisphere. There certainly is no whitewashing the kinds of activities that he ordered and that his government presided over that go against the very values that this country — that our country — has long defended.”

“To issue some sort of blistering statement and engage in the kind of mutual recriminations that are tied to the past — it doesn’t advance freedom or democracy,” he added.

Criticism from Trump and others, including South Florida Republican members of Congress, that Cuba has done little to reciprocate for the U.S.’ lifting of some travel, banking and commercial sanctions is “wrong,” according to Earnest.

“What we have seen is greater freedom for American citizens to visit Cuba, to send money to family members in Cuba, to engage in business and seek business opportunities in Cuba,” he said. “It also enhanced the ability of the United States government to maintain an embassy in Cuba where U.S. officials can more effectively not just engage with government officials in Cuba, but also those activists in civil society that are fighting for greater freedoms.”

Whether Trump would really maintain his hardline Cuba stance had been in question because, as a celebrity real-estate developer, Trump appeared keen on doing business in the island. His organization sent executives to Cuba as late as 2013 to explore building a golf course, in spite of the U.S. trade embargo that prohibits such investments.

As a candidate, Trump insisted he never followed through on any proposals to work in Cuba. During the campaign, Newsweek revealed Trump paid a consultant to check out potential opportunities in Cuba on his organization’s behalf in 1998.

Trump, who hasn’t given a news conference in five months, has yet to detail any Cuba specifics. He told the Miami Herald in August that he wasn’t prepared to weigh in on policies such as “wet-foot, dry-foot,” which allows Cubans who reach U.S. land to stay. He said only that he’d reject any effort by Cuba to seek reparations against the U.S. for losses the island might claim from the embargo.

The White House said Monday neither Obama nor Vice President Joe Biden will attend Castro’s funeral, though a U.S. delegation could travel to Cuba for the occasion.