The C.I.A. has said for years that it did not have enough information to conclude whether the Covid pandemic emerged naturally from a wet market in Wuhan, China, or from an accidental leak at a research lab there.

美国中情局几年来一直表示，它没有足够的信息来断定新冠大流行是从中国武汉的一个野生动物湿货市场自然产生的，还是那里的一个研究实验室意外泄漏的。

But the agency issued a new assessment this week, with analysts saying they now favor the lab theory.

但该机构本周发布了一份新的评估报告，分析人员表示，他们现在更倾向于实验室泄漏的推测。

There is no new intelligence behind the agency’s shift, officials said. Rather it is based on the same evidence it has been chewing over for months.

官员们表示，该机构的立场转变背后并没有新的情报。相反，它所依据的是几个月来一直在研究的相同证据。

The analysis, however, is based in part on a closer look at the conditions in the high security labs in Wuhan province before the pandemic outbreak, according to people familiar with the agency’s work.

不过，据熟悉该机构工作的人士透露，这一分析部分是基于对武汉的高安全等级实验室在大流行爆发前的条件进行的仔细研究。

A spokeswoman for the agency said the other theory remains plausible and that the agency will continue to evaluate any available credible new intelligence reporting.

该机构的一位发言人表示，另一种理论仍然可信，该机构将继续评估任何可信的新情报报告。

Some American officials say the debate matters little: The Chinese government failed to either regulate its markets or oversee its labs. But others argue it is an important intelligence and scientific question.

一些美国官员表示，这场辩论无关紧要：在规范市场和监督实验室这两件事上，中国政府都失败了。但也有人认为，这是一个重要的情报和科学问题。

John Ratcliffe, the new director of the C.I.A., has long favored the lab leak hypothesis. He has said it is a critical piece of intelligence that needs to be understood and that it has consequences for U.S.-Chinese relations.

美国中央情报局新任局长约翰·拉特克利夫长期以来一直支持实验室泄漏的假设。他表示这是一个需要弄清楚的重要情报，而且会对中美关系产生影响。

The announcement of the shift came shortly after Mr. Ratcliffe told Breitbart News he no longer wanted the agency “on the sidelines” of the debate over the origins of the Covid pandemic. Mr. Ratcliffe has long said he believes that the virus most likely emerged from the Wuhan Institute of Virology.

在中情局宣布这一转变不久前，拉特克利夫告诉布赖特巴特新闻网(Breitbart News)，他不再希望该机构在新冠大流行起源的争论中“袖手旁观”。他长期以来一直表示，他认为该病毒很可能来自武汉病毒研究所。

Officials said the agency was not bending its views to a new boss, and that the new assessment had been in the works for some time.

官员们表示，该机构并非因为新局长的到来而改变自己的观点，而且新的评估已经酝酿了一段时间。

In the final weeks of the Biden administration, Jake Sullivan, the national security adviser, ordered a new classified review of the pandemic’s origin. As part of that review, the agency’s previous director, William J. Burns, told analysts that they needed to take a position on the origins of Covid, though he was agnostic on which theory they should embrace, a senior U.S. intelligence official said.

在拜登政府执政的最后几周，国家安全顾问杰克·沙利文下令对大流行的起源进行新的机密审查。一位美国高级情报官员称，作为审查的一部分，中情局的前任局长威廉·伯恩斯告诉分析人员，他们需要对新冠起源表明立场，但他对他们应该接受哪种假设没有倾向性。

Another senior U.S. official said it was Mr. Ratcliffe’s decision to declassify and release the new analysis.

另一位美国高级官员称，解密和发布新的分析报告是拉特克利夫的决定。

Since the outbreak of the pandemic, questions have swirled around whether the two labs handling coronaviruses in Wuhan had followed safety protocols strictly enough.

自疫情暴发以来，武汉两所研究冠状病毒的实验室是否严格遵守了安全规程，一直备受质疑。

The agency made its new assessment with “low confidence,” which means the intelligence behind it is fragmentary and incomplete.

中情局以“低置信度”做出了新的评估，这意味着其背后的情报是零碎和不完整的。

Even in the absence of hard intelligence, the lab leak hypothesis has been gaining ground inside spy agencies. But some analysts question the wisdom of shifting a position in absence of new information.

即使在没有确凿情报的情况下，实验室泄漏假设在间谍机构内部也越来越得到认同。但一些分析人士质疑，在没有新情报的情况下转变立场是否明智。

Former officials say they are not averse to a new examination of the Covid origins intelligence by the Trump administration. President Biden ordered a new review of the intelligence early in his administration after officials told the White House they had still-unexamined evidence.

前官员表示，他们并不反对特朗普政府对新冠起源的情报进行重新审查。拜登总统在执政初期曾下令对情报进行新的审查，因为当时有官员告诉白宫，他们掌握了尚未审查的证据。

Mr. Ratcliffe has raised questions about politicization in the intelligence agencies. Mr. Ratcliffe, who was the director of national intelligence in the first Trump administration, argued in an essay for Fox News in 2023 that the C.I.A. did not want to embrace the lab leak to avoid geopolitical problems for the Biden administration.

拉特克利夫提出了关于情报机构政治化的问题。在特朗普的上一任政府中担任国家情报总监时，他在2023年为福克斯新闻撰写的一篇文章中指出，中情局不想接受实验室泄漏假设，以避免给拜登政府带来地缘政治问题。

“The real problem is, the only assessment the agency could make — which is that a virus that killed over a million Americans originated in a C.C.P.-controlled lab whose research included work for the Chinese military — has enormous geopolitical implications that the Biden administration does not want to face head-on,” he said in the piece, which was written with Cliff Sims, a top aide. C.C.P. refers to China’s Communist Party.

他在这篇与高级助手克里夫·希姆斯共同撰写的文章中表示：“真正的问题是，该机构所能做出的唯一评估——即导致一百多万美国人死亡的病毒源自一个由中国共产党控制的实验室，而该实验室的研究包括为中国军方工作——具有巨大的地缘政治影响，而拜登政府不想直面这种影响。”

Senator Tom Cotton, Republican of Arkansas and the new chairman of the Senate Intelligence Committee, has long said he thought the pandemic originated in one of the Wuhan labs and praised the shift in judgment by the agency.

阿肯色州共和党参议员、参议院情报委员会新任主席汤姆·科顿长期以来一直认为大流行病源于武汉的某个实验室，并对中情局判断的转变表示赞赏。

“Now the most important thing is to make China pay for unleashing a plague on the world,” Mr. Cotton said.

科顿称：“现在最重要的是让中国为向世界释放瘟疫付出代价。”

Mr. Ratcliffe said on Thursday, when he was sworn in, that a look at the origins of Covid was a “Day 1” priority.

拉特克利夫在上周四宣誓就职时表示，调查新冠起源是“第一天”的首要任务。

“I think our intelligence, our science and our common sense all really dictate that the origins of Covid was a leak at the Wuhan Institute of Virology,” he told Breitbart. “But the C.I.A. has not made that assessment or at least not made that assessment publicly. So I’m going to focus on that and look at the intelligence and make sure that the public is aware that the agency is going to get off the sidelines.”

“我认为，我们的情报、科学和常识都表明，新冠病毒源于武汉病毒研究所的泄漏，”他告诉布赖特巴特新闻。“但中情局并没有做出这样的评估，至少没有公开做出这样的评估。所以我要关注这一点，研究情报，确保公众知道该机构不再袖手旁观。”

Senior intelligence officials in the Biden administration defend their process and methodology. They have said that no intelligence was suppressed and insist that politics did not play into their analysis.

拜登政府的高级情报官员为他们的程序和方法做出了辩护。他们表示没有压制任何情报，并坚称政治因素没有影响他们的分析。

These officials say that there are powerful logical arguments for both the lab leak and the natural causes theories, but that there simply is no decisive piece of intelligence on either side of the issue.

这些官员称，实验室泄漏假设和自然原因假设都有强有力的逻辑论据，但无论哪一方都没有决定性的情报依据。

To boost the natural origins theory, intelligence officers would like to find the animal that passed it to a human or find a bat carrying what was the likely ancestor of the coronavirus that causes Covid.

要支持自然起源假设，情报人员希望找到将其传给人类的动物，或者找到携带了导致新冠病毒的可能原型的蝙蝠。

Similarly, to seal the lab leak, the intelligence community would like to find evidence that one of the labs in Wuhan was working on a progenitor virus that directly led to the epidemic.

同样，为了确认实验室泄漏假设，情报部门希望找到证据，证明武汉的某个实验室当时正在研究直接导致大流行的原生病毒。

Neither piece of evidence has been found.

这两项证据均未找到。

But Mr. Ratcliffe has promised a more aggressive C.I.A., and it is possible that he will order more actions to penetrate the labs in Wuhan or the Chinese government in a search for information.

但是，拉特克利夫已经承诺要让中情局变得更加积极，他有可能会下令采取更多行动，渗透到武汉的实验室或中国政府寻找信息。

It will not be an easy secret to steal. The senior ranks of the Chinese government do not know, and do not want to know, American officials have said. So if there is intelligence, it is probably hidden in a place that is hard to get to.

要窃取这个秘密并不容易。美国官员称，中国政府高层不知道，也不想知道真相。因此，如果有情报，很可能藏在一个难以获取的地方。

Intelligence officials interviewed in recent weeks say it is possible that such a piece of evidence exists in a lab in China, at least in theory. But, they said, it is still more likely that the answers to questions surrounding the virus’s origins will come through a scientific breakthrough, not an intelligence revelation.

最近几周接受采访的情报官员称，这样的证据可能存在于中国的某个实验室，至少在理论上是成立的。但他们说，更有可能的是通过科学突破而不是情报揭示来解答有关病毒起源的问题。

Under the Biden administration, the intelligence community leaned toward the theory that the virus came from the market. But officials readily admitted it was hardly a sure thing.

在拜登政府时期，情报部门倾向于病毒来自野生动物市场的假设。但官员们也坦率地承认，事实很难确定。

Five agencies, including the National Intelligence Council and the Defense Intelligence Agency, assessed that natural exposure most likely caused the epidemic. But they said that they had only low-confidence in their assessment.

包括国家情报委员会和国防情报局在内的五个机构评估认为，自然接触最有可能导致了大流行。但他们表示，对自己的评估只有低信心。

Until now, two agencies, the F.B.I. and Department of Energy, thought a lab leak was more likely. But their theories are different. The F.B.I. believes the virus came from the Wuhan Institute of Virology. The Energy Department put its bet on another lab, the Wuhan Center for Disease Control.

直到现在，联邦调查局和能源部这两个机构都认为实验室泄漏的可能性更大。但他们的假设是不同的。联邦调查局认为病毒来自武汉病毒研究所。能源部则认为是另一个实验室——武汉市疾病预防控制中心。

Officials would not say if the C.I.A. believes one lab or the other was the more likely source of the virus.

官员们不愿透露中情局是否认为这两个实验室中的一个更有可能是病毒的来源。