If it were not Snowden, all these NSA activities against civilians would remain a secret. Obama has said he welcomes a national debate on the issue, but he is only willing to do so now those programs have been exposed.

Obama will not say how many more such secret surveillance programs exist in the US, which explains why the US has been in such a hurry to hunt down Snowden before he discloses more programs like PRISM and XKeyscore.

For the past three years, public protests demanding the release of Manning have been taking place in many US cities. The 25-year-old faces up to 134 years in prison for telling the public about some of the horrible war crimes committed by the US in Iraq and Afghanistan.

What is ironic is that if Manning, Snowden and Assange were pursued by other governments, such as China and Russia, the White House and Foggy Bottom would be applauding them and calling them not just whistle-blowers, but heroes and fighters for human rights.

What is also ironic is that Assange, who has long advocated freedom of the press and opposed government censorship and who now lives in asylum in the Ecuadorean embassy in London, is being pursued by a government which likes to claim the same principles.

There is, of course, more irony. Many people now want to nominate Assange, Snowden and Manning for the Nobel Peace Prize, a laureate that Obama won in 2009 amid much controversy.

The US' harsh stance toward the three whistle-blowers is apparently intended to "kill a chicken to warn monkeys" to use a Chinese idiom. In this regard it has had the effect of putting pressure on journalists, especially those covering the national security beat, and potential whistle-blowers of US government's wrongdoings, to not delve too far into the murky world of "national security".

When I watched a ceremony on Wednesday afternoon staged by US Congressional leaders to mark the 50th anniversary of the March on Washington for Jobs and Freedom, I wondered if any of them still remembered Martin Luther King Jr's Letter from Birmingham Jail, in which he called on people to obey only the just laws and disobey the unjust ones. That is exactly what Manning, Snowden and Assange have done.

The author, based in Washington, is deputy editor of China Daily USA. chenweihua@chinadailyusa.com