China claims Taiwan is part of its territory and has threatened to use force to seize the island, stepping up military pressure and drills in recent years.

The intelligence community "assesses that Chinese leaders do not currently plan to execute an invasion of Taiwan in 2027, nor do they have a fixed timeline for achieving unification," said its Annual Threat Assessment report on Wednesday.

China's foreign ministry spokesman Lin Jian responded Thursday that "the Taiwan issue is China's internal affair" and urged the United States to "speak and act cautiously" on the island.

"The US should... correct their understanding of China, and stop hyping up the China threat theory," he told a press conference, in response to a question about the report.

Last year US officials at the Department of Defense had flagged 2027 as a possible timeline for an attack.

But the intelligence community has now offered a more measured analysis of the situation.

"In 2026, Beijing probably will continue seeking to set the conditions for eventual unification with Taiwan short of conflict," the report said.

But it cautioned that Chinese officials recognize that an amphibious invasion of Taiwan "would be extremely challenging and carry a high risk of failure, especially in the event of US intervention."

The report's authors said China publicly insists "unification with Taiwan is required to achieve its goal of 'national rejuvenation' by 2049", a much longer potential timeline to achieve its goals.

Beijing would consider a range of factors in any decision to invade Taiwan, it said, including its military readiness, the island's politics and whether or not Washington would intervene on Taiwan's behalf.

Washington does not officially recognize Taiwan, but is the island territory's main military backer -- although the tone of that support has softened slightly under US President Donald Trump.

A Taiwanese security official warned on Thursday that "it does not mean that the threat to Taiwan has ended."

China is "constantly adjusting its objectives and timelines for aggression and expansion in accordance with the overall strategic situation and practical conditions," the official said on the condition of anonymity.