Washington (CNN) President Donald Trump has actively cultivated an air of suspense around his upcoming summit with North Korean leader Kim Jong Un, but his decision last week to add another dose of reality-TV drama by teasing the release of three Americans currently being detained by the regime is raising concerns among former US diplomats.

Trump and his allies outside the government sought to fan heightened expectations surrounding the possibility of their release last week -- casting the potential development as evidence of the President's negotiating prowess ahead of a sit-down with Kim.

But experts and even some administration aides are worried the celebration may be premature and could send the wrong signals to Pyongyang or even jeopardize the prisoner's release.

"It doesn't take an expert to recognize that negotiations about detained US citizens can be extremely delicate," Mintaro Oba, a former Korea desk officer at the State Department under Obama, told CNN on Monday.

"Raising expectations in public is a dangerous game, one that can signal to the other country that you now have a lot more to lose if the deal falls through," he said.

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