WASHINGTON, Jan. 23 (Xinhua) -- Edward Snowden, a former U.S. defense contractor who revealed the U.S. secret surveillance programs, wrote on Thursday in an online chat that it is "not possible" for him to return to the United States under current whistleblower protection laws and he sees "no chance" to have a fair trial in his home country.

　　"Returning to the U.S., I think, is the best resolution for the government, the public, and myself, but it's unfortunately not possible in the face of current whistleblower protection laws, which, through a failure in law, did not cover national security contractors like myself," Snowden said, according to answers posted on the website of advocacy group "Free Snowden."

　　"This is especially frustrating, because it means there's no chance to have a fair trial, and no way I can come home and make my case to a jury," Snowden answered.

　　This is Snowden's second public online Q&A session since the first one hosted by the Guardian last June after he first revealed the U.S. National Security Agency's secret intelligence surveillance programs.

　　The 30-year-old former NSA contractor is currently living in Russia under temporary asylum and facing espionage charge for his leaks about the NSA surveillance practices in his home country.

　　Snowden, who regarded himself as a whistleblower of wrongdoing, also explained that current U.S. whistleblower protection laws in the U.S. "do not protect contractors in the national security arena."

　　"If we had had a real process in place, and reports of wrongdoing could be taken to real, independent arbiters rather than captured officials, I might not have had to sacrifice so much to do what at this point even the President seems to agree needed to be done," he said.

　　Snowden's latest public comments come after U.S. President Barack Obama offered his proposals to change the NSA controversial surveillance practices last Friday in a highly-anticipated and carefully worded speech.

　　In the speech, Obama outlined his plan to pull back part of the bulk collection of U.S. citizens' phone records while again highlighted his defense for the overall intelligence surveillance practices.

　　Snowden also echoed the points of a report released by a U.S. government privacy review panel on Thursday which concludes that the bulk collection of domestic phone records is not legal and " largely useless in thwarting terrorism."

　　"We have not identified a single instance involving a threat to the United States in which the program made a concrete difference in the outcome of a counterterrorism investigation," the Privacy and Civil Liberties Oversight Board's report wrote.

　　"There is simply no justification for continuing an unconstitutional policy with a 0% success rate," said Snowden during his online Q&A session.

　　However, the Obama administration has never called Snowden a whistleblower till now and suggested for several times that the young contractor should go to his supervisors instead of disclosing the classified information about the NSA programs.

　　In his speech last Friday, Obama also criticized Snowden's " sensational" way of disclosures that has often "shed more heat than light."

　　Hours before Snowden's Q&A session, U.S. Attorney General Eric Holder on Thursday said granting clemency for Snowden would be " going too far," NBC reported.

　　Instead, he said he would "engage in conversation" about a resolution with Snowden if the former NSA contractor accepted responsibility for leaking government secrets.

　　Obama has directed Holder and the intelligence community to develop options for a new approach of the domestic phone surveillance program without the government holding the metadata and report back to him before March 28. Part of the president's proposed reforms will also require authorization by Congress. It is not clear what measures will finally be taken into effect in the coming months.