In the United States, the term "deep state" describes a form of alleged cabal that coordinates efforts by government employees and others to influence state policy without regard for democratically elected leadership. The use of the term as applied to the United States has been dismissed by numerous journalists and academics as a conspiracy theory. The term has also been used to refer to alleged cabals in countries such as Turkey and post-Soviet Russia. In the United States, the term has been used in numerous published titles written by, for example, Marc Ambinder, David W. Brown, Peter Dale Scott, Mike Lofgren, and Michael Wolff.
The term gained popularity in some circles during the 2016 U.S. presidential election in opposition to establishment Republican and Democratic candidates, and has also been used in 2017 and 2018 during the Trump administration by commentators who argue that deep states are aiming to delegitimize the Trump presidency.
Deep state was defined in 2014 by Mike Lofgren, a former Republican U.S. congressional aide, as "a hybrid association of elements of government and parts of top-level finance and industry that is effectively able to govern the United States without reference to the consent of the governed as expressed through the formal political process." It has become a key concept of the alt right movement as expressed by Steve Bannon and Sean Hannity. 
In The Concealment of the State, professor Jason Royce Lindsey argues that even without a conspiratorial agenda, the term deep state is useful for understanding aspects of the national security establishment in developed countries, with emphasis on the United States. Lindsey writes that the deep state draws power from the national security and intelligence communities, a realm where secrecy is a source of power.Alfred W. McCoy states that the increase in the power of the U.S. intelligence community since the September 11 attacks "has built a fourth branch of the U.S. government" that is "in many ways autonomous from the executive, and increasingly so."
In the political journal Foreign Affairs, Jon D. Michaels discusses Trump and the deep state, and argues that the concept's relevance is quite limited in the United States. He is of the opinion that it is a more useful perspective in the study of developing countries such as Egypt, Pakistan and Turkey, "where shadowy elites in the military and government ministries have been known to countermand or simply defy democratic directives," but that "it has little relevance to the United States, where governmental power structures are almost entirely transparent, egalitarian, and rule-bound."
Recent popular usage of the term has led to its appropriation by Breitbart News and other conservative and right-wing news outlets, where supporters of the Trump Administration have used it to support a variety of conspiracy theories. It has been dismissed by authors for The New York Times and The Observer.University of Miami Professor Joseph Uscinski says, "The concept has always been very popular among conspiracy theorists, whether they call it a deep state or something else." 
The term "deep state" has been associated with the "military-industrial complex" by several of the authors on the subject. Potential risks from the military-industrial complex were raised in President Dwight D. Eisenhower's 1961 farewell address: "In the councils of government, we must guard against the acquisition of unwarranted influence, whether sought or unsought, by the military-industrial complex. The potential for the disastrous rise of misplaced power exists and will persist." Mike Lofgren has claimed the military-industrial complex is the private part of the deep state. However, Marc Ambinder has suggested that a myth about the "deep state" is that it functions as one entity; rather, that parts of the "deep state" are "often at odds with one another."
President Barack Obama's alleged lack of success of his campaign promises relating to the Afghanistan war and civil liberties has been attributed by Tufts University professor Michael J. Glennon to what he calls the "double government"; the defense and national security network. Mike Lofgren felt Obama was pushed into the Afghanistan "surge" in 2009. Another major campaign promise Obama made was the closure of Guantanamo Bay Prison Camp, which he was unable to accomplish. This has been attributed indirectly to the influence of the deep state. 
Donald Trump supporters use the term to refer to their allegations that intelligence officers and executive branch officials guide policy through leaking or other internal means. According to a July 2017 report by the United States Senate Committee on Homeland Security and Governmental Affairs, "the Trump administration was being hit by national security leaks 'on a nearly daily basis' and at a far higher rate than its predecessors encountered".
A number of commentators have also commented on the "deep state"-like influence wielded by career military officers such as HR McMaster, John Kelly and James Mattis in the Trump administration. This sub-presidential peer group has been sardonically described as an "axis of adults" (a reference to the "axis of evil" and Trump's supposed infantilism).
Following Trump's provision of "total authorisation" to the military and the subsequent use of a MOAB in Afghanistan, the anthropologist C August Elliott described the rise of a "shallow state" in the US: "an America where public servants now function as tugboats guiding the President's very leaky ship through the shallows, away from a potential shipwreck."
Donald Trump and Steve Bannon, his former chief strategist, have both made allegations about a deep state which they believe is interfering with the president's agenda. In 2018, describing the deep state as an "entrenched bureacracy," Trump accused the United States Department of Justice "of being part of the 'deep state'" in a statement advocating the prosecution of Huma Abedin. Some Trump allies and right-wing media outlets have alleged that former President Barack Obama is coordinating a deep state resistance to Trump. While the belief in a deep state is popular among Trump, his supporters and the Trump administration, critics dismiss it as a mere conspiracy theory and argue that the leaks frustrating the Trump administration lack the organizational depth of deep states in other countries, and that use of the term in the U.S. could be used to justify suppressing dissent.