The notion of a "war" against "terror" or "terrorism" has proven highly contentious, with critics charging that it has been exploited by participating governments to pursue long-standing policy objectives, reduce civil liberties, and infringe upon human rights. Some argue that the term war is not appropriate in this context, since they believe there is no identifiable enemy, and that it is unlikely international terrorism can be brought to an end by military means. The Director of Public Prosecutions and head of the Crown Prosecution Service in the United Kingdom, Ken McDonald has stated that those responsible for acts of terror such as the 7 July 2005 London bombings are not "soldiers" in a war, but "inadequates" who should be dealt with by the criminal justice system. Other critics, such as Francis Fukuyama, note that "terrorism" is not an enemy but a tactic; calling it a "war on terror" obscures differences between conflicts.
The term terrorism has been characterized as unacceptably vague. The United Nations Office on Drugs and Crime stated that there is lack of agreement on a definition of terrorism and that has proven to be an obstacle to meaningful international countermeasures. It proceeds to declare that "Some have often commented that one state's 'terrorist' is another state's 'freedom fighter'". Governments in Iran, Lebanon, and Venezuela consistently use the term "terrorism" to describe actions taken by the United States. The use of state terrorism by the US and the inherent hypocrisy of the term have been commented upon by Americans as well, including 3 star general William Odom, formerly President Reagan's NSA Director, who wrote:

"As many critics have pointed out, terrorism is not an enemy. It is a tactic. Because the United States itself has a long record of supporting terrorists and using terrorist tactics, the slogans of today's war on terrorism merely makes the United States look hypocritical to the rest of the world. A prudent American president would end the present policy of "sustained hysteria" over potential terrorist attacks..treat terrorism as a serious but not a strategic problem, encourage Americans to regain their confidence, and refuse to let al Qaeda keep us in a state of fright."

Further criticism maintains that the War on Terror provides a framework for perpetual war; the announcement of such open-ended goals produces a state of endless conflict, since "terrorist groups" can continue to arise indefinitely. George W. Bush pledged that the War on Terror "will not end until every terrorist group of global reach has been found, stopped, and defeated". During a July 2007 visit to the United States, newly appointed British Prime Minister Gordon Brown defined the War on Terror, specifically the element involving conflict with al-Qaeda, as "a generational battle".
The War on Terror has been criticized as inefficient, with a number of security experts, politicians, and policy organizations having claimed that the War on Terror has been counterproductive, that it has consolidated opposition to the US, aided terrorist recruitment, and increased the likelihood of attacks against the US and its allies. In a 2005 briefing paper, the Oxford Research Group reported that "Al-Qaida and its affiliates remain active and effective, with a stronger support base and a higher intensity of attacks than before 9/11. ...Far from winning the 'war on terror', the second George W. Bush administration is maintaining policies that are not curbing paramilitary movements and are actually increasing violent anti-Americanism." On September 19, 2008, the RAND Corporation presented the results of a comprehensive study for "Defeating Terrorist Groups" before the United States House Armed Services Committees, which said that "by far the most effective strategy against religious groups has been the use of local police and intelligence services, which were responsible for the end of 73 percent of [terrorist] groups since 1968." The RAND Corporation recommended "[The US military] should generally resist being drawn into combat operations in Muslim countries where its presence is likely to increase terrorist recruitment." They stated that "moving away from military references would indicate that there was no battlefield solution to countering terrorism."
Others have criticized the US for double standards in its dealings with key allies that are also known to support terrorist groups, such as Pakistan. Afghan President Hamid Karzai has repeatedly stated that in the "war against terrorism," “the central front is Pakistan"; Pakistan has also been alleged to provide Taliban operatives with covert support via the These accusations of double dealing apply to civil liberties and human rights as well as terrorism. According to the Federation of American Scientists, "[i]n its haste to strengthen the "frontline" states' ability to confront transnational terrorist threats on their soil, and to gain the cooperation of regimes of geostrategic significance to the next phases of the "War on Terrorism", the administration is disregarding normative restrictions on US aid to human rights abusers." Amnesty International has argued that the Patriot Act gives the US government free rein to violate the constitutional rights of citizens. The Bush administration's use of torture and alleged use of extraordinary rendition and black sites (secret prisons) have all fueled opposition to the War on Terror.
According to a sample survey conducted by the Pew Research Center, international support of the War on Terror has also faced a substantial decline, both in public opinion and by foreign state officials. In 2002, strong majorities supported the US-led War on Terror in Britain, France, Germany, Japan, India, and Russia. By 2006, supporters of the effort were in the minority in Britain (49%), France (43%), Germany (47%), and Japan (26%). Although a majority of Russians still supported the War on Terror, that majority had decreased by 21%. Whereas 63% of the Spanish population supported the War on Terror in 2003, only 19% of the population indicated support in 2006. 19% of the Chinese population supports the War on Terror, and less than a fifth of the populations of Turkey, Egypt, and Jordan support the effort. The report of the Pew Research Center also indicates that the Indian public support for the War on Terror has been stable. Andrew Kohut, speaking to the U.S. House Committee on Foreign Affairs, noted that, according to the Pew Research Center polls conducted in 2004, "majorities or pluralities in seven of the nine countries surveyed said the US-led war on terror was not really a sincere effort to reduce international terrorism. This was true not only in Muslim countries such as Morocco and Turkey, but in France and Germany as well. The true purpose of the war on terror, according to the people surveyed, is American control of Middle East oil and US domination of the world."
Stella Rimington, former head of the British intelligence service MI5, has criticized the war on terror as a "huge overreaction", and had decried the militarization and politicization of the US efforts as being the wrong approach to terrorism.In January 2009, the British Foreign Secretary, David Miliband, wrote that "ultimately, the notion is misleading and mistaken" and later said "Historians will judge whether [the notion] has done more harm than good"