It is unfortunate, but true that Americans cannot trust the statements of their leaders about threats to national security. Ironically, this is especially so when questions are being raised about the competence of the government or the legitimacy of its policies. The United States government has a long history of deflecting criticism by crying wolf, especially the terrorism kind of wolf.

On Friday, the US State Department issued a global travel alert after announcing it was closing 22 diplomatic missions in the Middle East and North Africa. US officials said they had intercepted electronic communications of al-Qaida operatives talking about attacking American interests in the region. Travelers were advised to "take every precaution to be aware of their surroundings" and to register their travel plans with the State Department.

There are several reasons to wonder if this threat is being concocted – or at least exaggerated – for political purposes. One reason, of course, is the timing of the alert. Allegedly based on electronic eavesdropping, the alert comes in the midst of a national and international political firestorm over the continuing revelations of Edward Snowden about the electronic surveillance programs of the National Security Agency. Opposition to the NSA dragnet that is sweeping up data on millions of Americans' emails, phone calls, and internet activities is snowballing in US public opinion and in Congress. The NSA programs have also become a major issue in the domestic politics of America's allies.

To say that the Obama Administration and US intelligence community are alarmed about these developments is a huge understatement. The nation's top leaders have been apoplectic in condemning Snowden as well as any nation that even mentions the possibility of offering him asylum. Both President Obama and Secretary of State John Kerry have been personally involved in trying to cut off Snowden's escape from American authorities.

While Russia Federation was considering Snowden's application for temporary asylum, the US Department of Justice made the embarrassing and telling promises that, if Snowden were returned to the US, he would not be tortured, deprived of a public trial with a jury, or subjected to the threat of capital punishment. These promises were necessary because all of these protections were denied to Bradley Manning, who, despite committing an essentially civilian crime of leaking evidence of war crimes to the press, was held in harsh conditions, charged with a capital offense, and tried by a military court with a judge and no jury.

Another reason for being suspicious about Friday's announcement of the travel alert and mission closures is the justification given for them in official statements. The travel alert is available on the Department of State's website. It says the US continues "to work closely with other nations on the threat from international terrorism" and "routinely" shares information with America's "key partners" in an effort "to disrupt terrorist plotting, identify and take action against potential operatives, and strengthen our defenses against potential threats". This reads likes a public relations statement for the people of Germany and the United Kingdom, who have expressed outrage not only at the NSA programs but also at the extent to which their own governments have cooperated with the NSA operations in their countries.

Third, the recent travel alert and mission closures warrant suspicion because of the US government's history of using terror alerts to manipulate public opinion. The Bush-Cheney Administration issued terror alerts at two key points in its first term. In May of 2002, Dan Rather accused administration officials of issuing a bogus terrorist alert for New York City. At the time, Rather was the anchorman for CBS nightly news, and a week earlier his network had reported that Bush had been briefed by the CIA in August 2001 about possible terrorist attacks on US soil involving airplane hijackings by al-Qaida. Democrats in Congress were calling for a 9/11 investigation. The alert in May, as Rather pointed out, effectively changed the subject.

The Bush-Cheney Administration also issued a series of terror alerts in the run-up to the 2004 presidential election. The president's popularity soared after 9/11, but it declined in 2003 and 2004 because of the invasion of Iraq, the fact that the administration's claims about Iraqi WMD proved false, and a major insurgency developed in Iraq after President Bush had declared "mission accomplished". However, Bush's popularity spiked upward whenever the terrorist threat level was raised from yellow to orange. After terror alerts were raised in 2003 and 2004 whenever Bush's numbers were low, speculations went viral in the blogosphere that the alerts were being timed politically to improve Bush's chances of reelection.

The administration's defenders dismissed these speculations as "conspiracy theories". In the United States, this retort is sufficient to silence stories in the mainstream media unless the accusations are supported by smoking-gun evidence of elite political intrigue. It was not until five years later, after Bush and Cheney were out of office, that the truth came out. Tom Ridge, who had served as Secretary of Homeland Security in the Bush-Cheney Administration, admitted in writing that he had been pressured to raise the alert levels to bolster Bush's popularity as the 2004 presidential election approached.

This is not the only example in modern American history of US leaders crying wolf to trigger a rally-around-the-president effect. As the 1964 presidential election approach, President Lyndon Johnson, a Democrat, was being blasted by Republican presidential candidate Barry Goldwater for not being sufficiently aggressive in Vietnam. The Johnson Administration responded by claiming inaccurately that North Vietnamese gunboats attacked a US ship in international waters near the Gulf of Tonkin. Congress passed the Gulf of Tonkin Resolution in October, the US sent combat troops to South Vietnam, and in November Johnson won by a landslide.

Other examples could be cited, but the important point is that people everywhere have good reasons to be suspicious when the US government issues warnings that have the effect of fomenting fear and quelling criticism. Dismissing doubts about possible intrigue on the grounds that they are "conspiracy theories" stymies debate when it is most needed.

In the months ahead, America and other democracies will be reconsidering the limits of government surveillance. Now is not the time to accept US government warnings uncritically. Quite the opposite, present circumstances call for the utmost vigilance against possible intrigue by officials who have proven to be less than candid and cautious in interpreting their legal authority and protecting, preserving, and defending the Constitution.