Elbridge Andrew Colby (born December 30,1979) is an American national security policy professional who is currently the under secretary of defense for policy. He previously served as deputy assistant secretary of defense for strategy and force development from 2017 to 2018 during the first Trump administration. He played a key role in the development of the 2018 U.S. National Defense Strategy,which,among other things,shifted the U.S. Defense Department's focus to China.
In June 2018,Colby was appointed as director of the Defense Program at the Center for a New American Security (CNAS). In 2019 he co-founded the Marathon Initiative,a grand strategythink tank,with Wess Mitchell. In December 2024,President-elect Trump nominated Colby to serve as the under secretary of defense for policy.
Identifying as a realist,Colby believes China is the principal threat faced by the United States. He believes the US should shift its military resources to Asia to prevent a Chinese takeover of Taiwan. Colby supports reducing military aid to Ukraine. During the AUKUS review in 2025,Elbridge pressured Australia to confirm what role it would play in a war with China over Taiwan.
In May 2017,Colby was appointed Deputy Assistant Secretary of Defense for strategy and force development,a role in which he served into 2018.[6] In this role,Colby was responsible for defense strategy,force development,and strategic analysis for policy for the secretary of defense.[5] Colby served as the primary Defense Department representative in the development of the 2017 National Security Strategy.[10]
While deputy assistant secretary,Colby served as the lead official in the development and rollout of the department's strategic planning guidance,the 2018 National Defense Strategy (NDS). The NDS posited:"Inter-state strategic competition,not terrorism,is now the primary concern in U.S. national security," and "the central challenge to U.S. prosperity and security is the reemergence of long-term strategic competition," primarily from China and Russia.[11] Going further,Colby said the "central challenge facing the department of defense and the joint force [is] the erosion of U.S. military advantage vis a vis China and Russia."[12]
Politico reported that in re-orienting American defense resources away from the Middle East and towards China,Colby faced considerable bureaucratic infighting from U.S. Central Command and the Joint Staff,but received support from the Air Force and the Navy.[6]
Interlude
After leaving the Department of Defense in 2018,Colby returned to the Center for a New American Security (CNAS),where he continued to work on defense issues until 2019.[13] He then launched The Marathon Initiative,a think tank devoted to developing strategies for the US to compete with global rivals.[6][10][14]
In 2021,Colby expanded on his views in his first book,The Strategy of Denial:American Defense in an Age of Great Power Conflict,which The Wall Street Journal named a Ten Best Book of 2021.[6][15]
Second Trump administration
Nomination and confirmation
Colby with Indian Foreign Secretary Vikram Misri and Deputy National Security Advisor Pavan Kapoor in May 2025.
On December 22,2024,President-elect Trump nominated Colby to serve as the under secretary of defense for policy for his second term as president.[16][17] Despite the support of influential MAGA figures like Vice PresidentJD Vance and influencer Charlie Kirk,his nomination drew criticism from Republican Party defense hawks like Senator Tom Cotton regarding his past comments that Iran's acquisition of a nuclear weapon would not be an existential risk for the United States.[18] During his hearing before the United States Senate Committee on Armed Services on March 4,2025,Colby said he would not hesitate to advise Trump on military options to stop Iran's nuclear program if necessary. He also confirmed his intention to increase U.S. military resources in the Indo-Pacific and called on Taiwan to increase its defense budget from 2.5% of GDP to 10%.[19]
Colby's nomination was confirmed by a 54-45 Senate vote on April 8,2025.[20] Senator Mitch McConnell was the only Republican to oppose Colby's nomination,leading to criticism from Republicans including JD Vance and Nate Morris.[21]
Tenure
In May 2025,Colby told British officials that the United States wanted the British Armed Forces to focus less on the Indo-Pacific and more in the Euro-Atlantic region. He also expressed concern about the UK sending the HMS Prince of Wales to the Indo-Pacific.[22] In June 2025,Colby pushed for the Department of Defense to launch a review whether to scrap the AUKUS agreement with Australia and the United Kingdom.[23] Colby also pushed for Japan to increase its military spending to 3.5% of its GDP,which led Japan to cancel a meeting between U.S. Secretary of State Marco Rubio and U.S. Defense Secretary Pete Hegseth and Japanese Defense Minister Gen Nakatani and Foreign Minister Takeshi Iwaya in Washington,D.C.[24]
In early July,the US paused deliveries of various munitions to Ukraine,an initiative that reportedly originated from Colby;both Congress and the State Department were not aware of the decision.[25] Additionally,members within the Trump administration were not consulted on the halting of the arms shipments,with Trump himself claiming to be unaware of the decision.[26] Trump later reinstated the arms shipments within days.[27] Afterwards,a bi-partisan group of members of Congress demanded an explanation from Colby.[28] After the European-White House crisis meeting was held in August 2025,Trump announced the US could provide security guarantees to Ukraine as part of a peace agreement to end the Russo-Ukrainian war. Colby reportedly told representatives of European allies that the US would play a minimal role in any security guarantees.[29] Later that month,Ukraine was denied long-range missile strikes on Russia under a “review mechanism”that had been developed by Colby.[30]
Political views
Colby identifies as a realist. He believes that China is the principal threat faced by the United States,and that Asia should be the priority of U.S. efforts and resources.[31] He advocates for the U.S. to shift its military planning and resources to prepare for a conflict over Taiwan,and supports bolstering U.S. industrial capacity.[6][31] In a Time article he co-authored with Heritage Foundation president Kevin Roberts,Colby wrote that:"[W]e need to be absolutely clear:Without question,the top external threat to America is China—by far."[32] He is a "prioritizer," believing the U.S. to have limited military resources,and thus supporting a reorientation of U.S. military resources away from the Middle East and Europe to Asia and China.[33]Foreign Policy describes him as "the loudest and perhaps most cogent voice in Washington advocating a complete shift away from Europe,NATO,and Russia and toward the growing challenge from China".[34]
Asia
Elbridge Colby with members of the Japanese Diet in April 2025.
Colby believes China is seeking regional hegemony over Asia,which he believes to be the world's most important region,and will achieve that goal if not stopped by the U.S. He says that if China is allowed to dominate Asia,it would severely diminish America's future prospects and freedom of action,push the American economy down the value chain,and leave the U.S. less resistant to Chinese pressure.[31][34] He believes the most effective way for China to achieve regional hegemony would be by attacking a U.S. ally or quasi-ally,which he identifies as Taiwan. He advocates for a "strategy of denial" to deny regional hegemony to China and stopping or defeating a potential invasion of Taiwan. He believes an attack on Taiwan would lead to a "limited war" which would seek to cause the least upheaval in the region,with no motivation on either side to escalate;he calls on the U.S. to prepare for this scenario. He further calls for an "anti-hegemonic coalition" made up of U.S. allies in Asia to stop China from taking over Taiwan;he believes that if the coalition failed to stop a takeover of Taiwan,China could seize the Philippines and Vietnam next. Colby also advocates for an end to U.S. policy of strategic ambiguity on Taiwan.[31][35] He believes Taiwan should raise its military spending to 10% of its GDP and has called for the destruction of TSMC to keep it out of Chinese control should Chinese military forces capture Taiwan.[36] While Colby believes Taiwan is important to the US,he doesn't consider it to be an "existential interest" and thinks the "core American interest is in denying China regional hegemony".[37]
Colby with South Korean Deputy Defense Minister Cho Chang-rae in May 2025.
Colby has to date claimed that he hopes for the US to scale back its support of Ukraine and to instead focus on China as America’s primary geopolitical threat. Yet there is good reason to disbelieve this claim. It is instead more probable that Colby is simply using China as a pretext to scale back US commitments more broadly.
Brian Hioe, in New Bloom Magazine, 28 July 2025.[38]
Despite his reputation as a China hawk, Colby does not describe the Chinese Communist Party (CCP) or CCP general secretaryXi Jinping as "evil" and rejects a "cartoonish account" of China as "unstoppably rapacious", believing China to be a "rising power" with "a rational interest in expanding their sphere and believing themselves to be aggrieved and put upon". He supports treating China with respect and a "strong shield of disincentive", continuing by saying that his policy is "status quo. My strategy is not designed to suppress or humiliate China… I believe China could achieve a reasonable conception of the rejuvenation of the great Chinese nation, consistent with the achievement of my strategy. If you put all that together, that looks like somebody who is advocating for peace based on a realistic reading of the world."[31] He also believes the U.S. should not seek to change China's internal politics or ideological system as long as China does not seek regional hegemony.[35]
Colby supports deprioritizing North Korea, telling Yonhap News Agency in May 2024 that the "fundamental fact is that North Korea is not a primary threat to the U.S." and it "would not be rational to lose multiple American cities to just deal with North Korea".[39] He called on South Korea to take "overwhelming responsibility" for its own defense against North Korea, with the U.S. getting involved only if China gets involved. He also said United States Forces Korea should be focused on protecting South Korea from possible Chinese attacks instead of being "held hostage to dealing with the North Korean problem". He supports transferring wartime operational control from the U.S. to South Korea, while signaling his openness to South Korea acquiring nuclear weapons. He said the denuclearization of North Korea was an "impossibly far-fetched" idea, instead calling to focus on more "attainable" goals such as arms control focused on limiting the range of North Korean intercontinental ballistic missiles.[40] He advocates for Japan to spend more on its military, telling The Nikkei in September 2024 that Japan should spend 3% of its GDP on military.[41]
Europe
If he [Colby] has his way — irrespective of what Trump does tomorrow or the day after — America will keep weaning itself from Europe and the Middle East, and eventually cease being a global leader to become a North American and Pacific power.
Andreas Kluth on Colby, in a Bloomberg opinion piece, July 2025.[28]
Colby believes aiding Ukraine during the Russian invasion of Ukraine jeopardizes America's focus on China. In 2023, he told Politico that "Ukraine should not be the focus. The best way to avoid war with China is to be manifestly prepared such that Beijing recognizes that an attack on Taiwan is likely to fail. We need to be a hawk to get to a place where we can be a dove. It's about a balance of power".[6] Colby later wrote that "it is in America's interest to avoid [Ukrainian defeat], but we must pursue that interest in a manner consistent with our highest priority of restoring a formidable denial defense along Asia's first island chain."[42] He opposes Ukraine's membership in NATO.[43] Colby instead supports European countries to commit more resources on countering Russia and bolstering their militaries, allowing the U.S. to shift its resources on Asia.[31] Colby has repeatedly expressed skepticism toward AUKUS and has reactively negatively to the deployment of a UK carrier strike group to the Indo-Pacific.[44] He believes European NATO members should spend around 3 to 4 percent of their GDP on defense and says the U.S. should be "prepared to use carrots and sticks to incentivize the right kind of behavior from our point of view" in regards to European countries.[45]
Middle East
Colby supports a reduction of U.S. military presence in the Middle East, a region which he described as "relatively unimportant" from a geopolitical standpoint. He supports withdrawing the U.S. military from the Persian Gulf, arguing the U.S. can counter Iran "more efficiently" by "bolstering the military capabilities of its partners in the region". He opposes direct military action against Iran, while arguing that containing an Iran with nuclear weapons "is an entirely plausible and practical objective. In an article written shortly before the 7 October Hamas-led attack on Israel, Colby called for a "reset" in America's relationship with Israel, saying America should "defer more to Israel's judgement about how to best manage its security challenges", and that while the US should be prepared to provide material and political support to Israel, it should understand that the US., which "cannot afford to be enmeshed in another Middle Eastern war, will take a supporting role." He later questioned the Biden administration's efforts to counter the Houthis in Yemen.[33]
Personal life
Colby is married to Susanna Colby.[46] He is Catholic.[47]
Selected publications
The Strategy of Denial: American Defense in an Age of Great Power Conflict (Yale University Press, 2021)[48]
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