WASHINGTON — Just weeks after President Biden took office, North Korea sent a subtle message to the new administration: It switched on key parts of its nuclear fuel production plant in Yongbyon, the aging complex where the country’s nuclear weapons program was born four decades ago.

华盛顿——就在拜登总统上任几周后,朝鲜向美国新政府发出了一个微妙的信息:它启动了宁边核燃料制造厂的关键部分,40年前,朝鲜的核武器计划就始于这处日益老化的设施。

North Korean officials knew the heat signatures from their radiochemical laboratory would light up American satellites overhead and make it into the President’s Daily Brief, even if it was not clear whether the move was a deceptive fake or a sustained new round of production.

朝鲜官员都明白,出自他们放射化学实验室的热信号会被头顶的美国卫星发现,进入总统每日简报,哪怕对方并不清楚这一举动是幌子还是新一轮的持续生产。

“It’s part of the playbook,” said Victor Cha, who released an analysis of the images for the Center for Strategic and International Studies. “It says we are here to stay.”

“这都是策略的一部分,”车维德(Victor Cha)说,他为战略与国际研究中心(Center for Strategic and International Studies)发布了一份对这些卫星图像的分析报告。“意思是这已经是既成事实。”

The staying power of Pyongyang’s nuclear arsenal highlights an uncomfortable truth for Mr. Biden as he prepares to greet President Moon Jae-in of South Korea at the White House on Friday. Mr. Moon has said denuclearization of the Korean Peninsula is a “matter of survival” for his country, and he has called on Mr. Biden to revive negotiations.

对准备周五在白宫接待韩国总统文在寅(Moon Jae-in)的拜登来说,平壤核武库的持久力量凸显了一个不安事实。文在寅曾表示,朝鲜半岛的无核化对韩国来说是“生死攸关的问题”,他也呼吁拜登重启谈判。

But North Korea’s arsenal of nuclear weapons and its stockpile of fuel have roughly doubled in the past four years, a steady rise that proceeded even as President Donald J. Trump held high-drama meetings with Kim Jong-un, the North Korean leader. The best unclassified estimates are that the North has at least 45 nuclear weapons, and appears headed to an arsenal roughly the size of Pakistan’s, another nuclear state the United States once demanded must disarm, and now has all but given up that it ever will. For the North, that has always been a model to follow.

但在过去四年,朝鲜的核武库和核燃料储备大约翻了一番,尽管唐纳德·J·特朗普(Donald J. Trump)总统与朝鲜领导人金正恩(Kim Jong-un)高调举行了会晤,这种增长仍在持续进行。最好的非机密评估是朝鲜至少有45件核武器,武器库规模似乎与巴基斯坦相当,后者是美国曾经要求必须解除核武器的另一个核国家,而今已彻底放弃了这一希望。对朝鲜来说,巴基斯坦一直是个效仿对象。

In private, officials in the Biden administration admit they harbor no illusions that North Korea will ever give up the entirety of its program. Yet, like his predecessors, Mr. Biden has made the decision not to officially acknowledge the North as a nuclear state, aides say.

拜登政府的官员私下里承认,他们对朝鲜会彻底放弃全部核计划不再抱有幻想。然而助手们表示,就像他的前任一样,拜登已经决定不会正式承认朝鲜是一个核国家。

Robert J. Einhorn, a former State Department official who was long a nuclear expert for the agency, said a formal acknowledgment that North Korea is a nuclear state would “increase interest by South Korea and Japan in acquiring their own nuclear weapons” and “damage the global nonproliferation regime.” So he said he expected the administration would use the visit to “reaffirm complete denuclearization” as the ultimate goal, “even if it privately doubts that goal will ever be achieved.”

曾在国务院任职、长期以来一直是国务院核专家的罗伯特·J·艾因霍恩(Robert J. Einhorn)表示,正式承认朝鲜是核国家会“增加韩国和日本对获得自身核武器的兴趣”,并“破坏全球核不扩散机制”。因此,他预计拜登政府将利用这次访问“重申完全无核化”的最终目标,“哪怕私下怀疑这一目标可能永远不会实现”。

For months now, the Biden administration has been engaged in a North Korean strategy review, often in consultation with South Korea and Japan. But it has offered little detail in public about its conclusions, other than to avoid trying a grand bargain with Mr. Kim that Mr. Trump did. Instead of trying to wrap a peace treaty formally ending the Korean War, the promise of a new relationship between Pyongyang and Washington, and a sweeping disarmament plan into one package, it will turn back to small, confidence-building steps.

数月以来,拜登政府一直在进行朝鲜问题的战略评估,经常与韩日磋商。但政府并未公布结论细节,只是避免了像特朗普那样试图向金正恩做出重大妥协。它不会试图把正式结束朝鲜战争的和平条约、平壤与华盛顿之间建立新关系的承诺以及解除核武器的全面计划揉到一起,而是将回到一小步一小步建立信任的办法上。

Mr. Moon’s meeting is the second in-person visit of a world leader to the White House. He was crucial in arranging the summits between Mr. Trump and Mr. Kim, and has continued to encourage dialogue between Washington and Pyongyang. While at the White House, he is expected to reiterate those goals, while emphasizing with Mr. Biden a series of South Korean investments in the United States in semiconductors and batteries for electric cars — ways of deepening the technological alliance at a moment of heightened competition with China.

与文在寅的会晤是第二次有世界领导人亲自访问拜登入主后的白宫。他在安排特朗普与金正恩的会面中发挥了关键作用,并继续鼓励华盛顿与平壤之间的对话。预计他将在白宫重申这些目标,同时与拜登共同强调韩国在美国对半导体和电动汽车电池行业的一揽子投资——这是在与中国竞争加剧之际深化技术联盟的途径。

3月,首尔一家电器商店的电视屏幕中播放着朝鲜导弹的资料影像。

The result is that Mr. Biden is not likely to dwell much on North Korea, at least in public, Mr. Cha said.

车维德表示,这样一来拜登也不太可能过多谈论朝鲜,至少在公开场合不会。

“They will change the topic,” he said.

“他们会改变话题,”他说。

And officials in the Biden administration have made clear they are not interested in giving Mr. Kim the satisfaction of being the center of attention, as he was during his dramatic meetings with Mr. Trump in Singapore, in Hanoi, Vietnam, and at the Demilitarized Zone.

拜登政府的官员们已经明确表示,他们无意让金正恩因成为焦点而志得意满,就像他在新加坡、越南河内以及朝韩非军事区与特朗普高调会面时那样。

But the Biden White House has not thrown out all of Mr. Trump’s diplomacy.

但拜登政府并没有彻底摒弃特朗普的所有外交政策。

The White House says it wants to build on the “Singapore declaration,” which called for a new relationship between the United States and North Korea, a permanent peace plan, complete denuclearization and a full accounting of soldiers missing in action from a war that ended nearly seven decades ago.

白宫表示,希望在新加坡宣言的基础上取得进展,这一宣言呼吁美朝建立新关系,制定永久和平计划,实现完全无核化,并全面统计在约70年前结束的战争中失踪的士兵。

The document is only one page, and it is not specific about how to achieve those objectives. Mr. Trump, speaking in Singapore in June 2018, told reporters that the relationship with Mr. Kim would make all the difference. “Honestly, I think he’s going to do these things,” he said.

这份文件仅有一页内容,且没有具体说明如何实现这些目标。2018年6月,特朗普在新加坡发表讲话,对记者称自己与金正恩的关系将改变一切。“老实说,我认为他会做到这些事,”他说。

For the most part, Mr. Kim has failed to follow through, though he has maintained a promised moratorium on long-range missile tests and made some progress on the return of remains. But the fact is that he did not dismantle a single weapon, and the nuclear production program sped up.

尽管坚持了暂停远程导弹试验的承诺,并在遗骸归还问题上取得了一些进展,但对大部分目标,金正恩都未能履行承诺。事实却是,他没有解除任何一件核武器,核生产项目也在加速。

In the past several years, Pyongyang roughly doubled its supplies of fuel that can be turned into nuclear weapons, according to analysts. It did so mainly at the Yongbyon complex, where the nuclear program began in the 1960s. Today, the site’s many hundreds of industrial buildings cover an area of more than three square miles.

分析人士称,平壤在过去几年将可用于制造核武器的燃料供应量增加了大约一倍。这主要就在宁边的设施里完成的,那里的核项目始于上世纪60年代。如今,这里有数百座工业建筑,占地面积超过三平方英里。

2018年,唐纳德·J·特朗普总统与朝鲜领导人金正恩在新加坡会面。他们签下了一份只有一页、缺乏细节的协议,朝鲜基本上无视了这份协议。

Siegfried S. Hecker, a former director of the Los Alamos weapons laboratory in New Mexico who is now a Stanford professor, cast the fuel rise in terms of potential weapons: In 2000, at the end of the Clinton administration, Pyongyang had no nuclear arms. In 2008, at the end of the Bush administration, it had four to six. In 2016, at the end of the Obama administration, it had roughly 25. In 2020, at the end of the Trump administration, it had about 45 and perhaps as many as 60.

曾担任新墨西哥州洛斯阿拉莫斯武器实验室主任的斯坦福大学教授西格夫里·S·赫克(Siegfried S. Hecker)用燃料增长计算了朝鲜可能的核武器数量:2000年,在克林顿政府末期,平壤还没有核武器。2008年布什政府末期有四到六件。2016年,奥巴马政府离任时,大约为25件。2020年,在特朗普政府末期,其数量约在45件,最高或达到60件。

“The policies of the past three presidents have failed,” Dr. Hecker said in an email. “Unless the Biden team changes course, North Korea will continue to expand the size, sophistication and reach of its nuclear arsenal.”

“过去三任总统的政策都失败了,”赫克在一封电邮中说。“除非拜登团队改变策略,否则朝鲜将继续增加其核武库的规模、尖端技术和覆盖范围。”

In size, experts say, the North’s stockpile of nuclear arms is fast approaching those of India, Pakistan and Israel — relatively small members of the club who are seen as deploying about a hundred or so weapons, whereas the big players have thousands. That is the model the North is pursuing: No one expects any of those countries to give up their nuclear arsenals.

在规模方面,专家称朝鲜的核武库正在迅速接近印度、巴基斯坦和以色列的规模——这是个规模相对小的集团,通常认为部署了约100件左右的核武器,而大国一般有数千件。这就是朝鲜想要达成的模式:谁也不会指望这一类国家会放弃核武库。

On Mr. Trump’s watch, new missiles also came to life. In 2017, Pyongyang for the first time successfully test-fired two kinds of intercontinental ballistic missiles — both, in theory, able to drop warheads on the United States. In June 2018, Mr. Kim told Mr. Trump that he would stop testing his long-range missiles and nuclear arms. So far, he has kept those promises.

在特朗普任内,朝鲜获得了新型的导弹。2017年,平壤首次成功试射两种洲际弹道导弹——理论上都可以将核弹头投放到美国。2018年6月,金正恩对特朗普说他会停止远程导弹和核武器的试验。这个承诺他至今仍保守着。

But Mr. Kim has also proceeded to introduce new generations of shorter-range missiles, capable of targeting South Korean, Japanese and American forces based in the two countries.

但是金正恩此后又拿出了两代射程较短的新型导弹,可以打击韩国、日本和驻扎在这两个国家的美军。

During the Trump years, experts were able to look at satellite images at 16 of Pyongyang’s missile bases, which were much camouflaged. They found inconspicuous patterns of growth that suggested the North had engaged in a great deception: curbing its long-range missile program while expanding its ability to pummel nearby rivals with conventional and nuclear warheads.

在特朗普任期内,专家们能看到平壤的16个导弹基地的卫星图片,都进行了充分伪装。他们发现了隐蔽的增长模式,表明朝鲜在进行瞒天过海的行动:一方面暂停远程导弹计划,另一方面在扩大用常规弹头和核弹头威胁邻近敌国的能力。

Mr. Kim test fired three new missiles in 2019 and one this year. Those models, analysts say, have greater accuracy and new maneuvering powers that could help the warheads outwit American defenses in the region.

金正恩在2019年试射了三枚新型导弹,今年试射了一枚。分析师称这些型号的精度更高,并具备此前没有的机动能力,有助于让弹头突破美国在该地区的防御。

“They’ll probably end up being able to strike more targets,” Vann H. Van Diepen, a former weapons analyst for the National Intelligence Program, said of the new missiles in an interview.

“他们可能最终将具备打击更多目标的能力,”前国家情报项目(National Intelligence Program)武器分析师凡·H·范·蒂耶彭(Vann H. Van Diepen)在一次采访中这样评价新型导弹。

由战略与国际研究中心提供的注解图片显示了朝鲜宁边核设施的卫星热成像。

The differences between the United States and North Korea on how to achieve a nuclear-free Korean Peninsula have grown all but unbridgeable over the years. But a strong voice arguing that the gap can be narrowed through continued dialogue has been Mr. Moon, who assumed the role of mediator and cheerleader during the Trump administration.

美朝两国在朝鲜半岛无核化的实现方式上存在的分歧,近年来已经到了无法弥合的程度。不过有一个声音一直在坚称,持续对话可以拉近双方的距离,那就是文在寅。在特朗普任期内,他担负起了调停人和啦啦队员的角色。

Even after the summit meetings between Mr. Kim and Mr. Trump ended without an agreement, Mr. Moon’s government insisted engagement was the only viable way to end the nuclear threat and establish peace.

即便金正恩和特朗普的首脑会谈在没有达成协议的情况下收场,文在寅政府还是坚持认为,双方保持接触是终结核威胁、实现和平的唯一可行途径。

In an interview in April with The New York Times, Mr. Moon urged the Biden administration to start negotiations with North Korea, and build on the broad goals outlined by Mr. Kim and Mr. Trump.

在4月接受时报采访时,文在寅呼吁拜登政府与朝鲜展开谈判,朝着金正恩和特朗普构想的广泛目标去努力。

This month, after Washington released its North Korea policy review, Mr. Moon said he saw no difference between the two allies’ approach to North Korea. Both countries intended to build on the Singapore agreement and take “diplomatic, gradual, phased, practical and flexible” steps toward the ultimate goal of denuclearizing the Korean Peninsula.

本月在华盛顿公布朝鲜政策复核报告后,文在寅称美韩这对盟友在朝鲜问题上并无分歧。两国都希望在新加坡共识的基础上继续发展,采取“外交的、逐步的、渐进的、务实的、灵活的”步骤,最终实现朝鲜半岛无核化。

When he sits down this week with Mr. Biden, Mr. Moon said, one goal would be bringing North Korea “back on the path of dialogue.”

文在寅说,本周与拜登会谈时,他会说其中一个目标是让朝鲜“回归到对话的轨道上来”。

But those mutual interests have limits. For its part, the Biden administration has aimed to deepen Washington’s strategic partnership with South Korea and draw it into the evolving American strategy to compete with China. It is a delicate dance because of South Korea’s enormous trade relationship with Beijing.

但是双方的共同利益也存在局限。拜登政府方面意在加深华盛顿与韩国的战略合作,以动员该国参与到美国与中国竞争的战略中。考虑到韩国与北京之间有着深厚的贸易关系,这是一个非常微妙的局面。

周五,韩国总统文在寅将在华盛顿与拜登会面。