(CNN) -- Pleading for asylum from U.S. officials he says want to persecute him, NSA leaker Edward Snowden told Ecuadorian officials that he fears a life of inhumane treatment -- even death -- if he's returned the United States to answer espionage charges, the country's foreign minister said Monday.
Snowden, the computer contractor who exposed details of secret U.S. surveillance programs, told Ecuadorian President Rafael Correa that it is "unlikely that I will have a fair trial or humane treatment" if handed over to U.S. officials to stand trial, according to a letter from Snowden read by Foreign Minister Ricardo Patino.
While Patino, speaking at a news conference in Vietnam, said the country has yet to decide on Snowden's asylum request, he questioned whether it was Snowden or the United States that was acting badly in the affair.
He called the surveillance programs revealed by Snowden "a breach of the rights" of people around the world.
"We have to ask, who has betrayed who?" he said.
Correa, meanwhile, took to Twitter to address the issue. "Rest assured that we will analyze the Snowden case very responsibly and we will make with absolute sovereignty the decision that we believe is most appropriate," the president tweeted.
He added, "A big hug to everyone and happy week."
Snowden -- whose passport has been revoked by U.S. authorities -- left Hong Kong Sunday on a "refugee document of passage" issued by Ecuador, according to Julian Assange, founder of the anti-secrecy group WikiLeaks, which is aiding Snowden in his efforts to find a safe haven.
Russian officials confirmed that he had flown to Moscow, where he spent the night at Sheremetyevo International Airport, according to media reports. It was unclear where he was Monday, but White House spokesman Jay Carney said U.S. officials presume he remains in Russia.
Assange would say only that the former National Security Agency contractor is "in a safe place and his spirits are high."
In addition to Ecuador, Snowden is asking Iceland and other, unspecified countries to consider granting him asylum, WikiLeaks attorney Michael Ratner told reporters Friday.
Iceland has not received a formal application from Snowden, the Interior Ministry said Monday.
Snowden had been expected to board a flight to Cuba on Monday, Russia's semiofficial Interfax news agency reported. But a CNN journalist on a flight to Cuba said Snowden did not appear to be in the cabin. Interfax later reported that he did not board the plane and may be planning on taking the next flight to Cuba.
Officials at the airport declined Monday to say whether Snowden remained there.
Meanwhile, U.S. officials cast a wide net seeking his return, telling Russia and Latin American countries that they should hand Snowden over should he land on their soil.
President Barack Obama told reporters Monday that the United States is pursuing all legal channels to bring Snowden back. And Carney said U.S. officials are reaching out to numerous countries in an effort to have Snowden turned over.
"The U.S. is advising these governments that Mr. Snowden is wanted on felony charges and as such should not be allowed to proceed in any further international travel other than is necessary to return him here to the United States," he said.
But CNN legal analyst Jeffrey Toobin said the issue now "is much more of a political and diplomatic matter than it is a legal matter."
"In an ordinary case, sure, you need a passport to get around," Toobin said. "But here, where this case is causing increasing embarrassment for the United States, governments that want the United States to be embarrassed are only too happy to waive some of the technical legal rules."
Secretary of State John Kerry particularly urged Russian authorities to work with the United States, noting that U.S. officials have turned over seven prisoners to Russia in recent years.
"We need to cooperate on this because it's important to the upholding of the rule of law," he told CNN.
He defended the U.S. effort to capture Snowden for prosecution, saying "people may die as a consequence of what this man did."
Meanwhile. FBI Director Robert Mueller called his counterpart at Russia's Federal Security Service twice Monday concerning Snowden, a senior administration official said.
In Washington, a Justice Department official told CNN that the United States isn't planning to ask for a "red notice" calling on members of the international police agency Interpol to take Snowden into custody.
The official, however, declined to say if the United States has sent or will send provisional arrest warrants to other countries that might take Snowden in or help him in his travels.
Ecuador 'analyzing' request
It seems unlikely that Cuba, Venezuela or Ecuador -- the nations on Snowden's potential itinerary -- would be inclined to send him back to the United States.
The U.S. government has already asked those three Latin American countries to not admit Snowden or to expel him if they do, a senior Obama administration official told CNN on Sunday.
But Cuba and Venezuela have long had strained relations with Washington. And Ecuador has given Assange refuge in its embassy in London for a year after he unsuccessfully fought extradition to Sweden in British courts.
Assange say he fears Sweden, which wants him for questioning about sexual assault allegations, would transfer him to the United States.
In his letter, read by Patino, Snowden compared himself to Pvt. Bradley Manning, the U.S. soldier accused of leaking classified information through WikiLeaks.
He said U.S. officials have treated Manning inhumanely by holding him in solitary confinement, and he predicted a similar "cruel and unusual" fate for himself if he falls into U.S. hands.
Assange, speaking to reporters on a conference call, accused the United States of trying to bully other nations into handing over Snowden, whom he referred to as a "whistle-blower who has told the public an important truth."
"The Obama administration was not given a mandate by the people of the United States to hack and spy upon the entire world, to breach the U.S. Constitution and the laws of other nations in the manner that it has," Assange said. "To now attempt to violate international asylum law by calling for the rendition of Edward Snowden further demonstrates the breakdown in the rule of law by the Obama administration, which has sadly become so familiar to so many."
Assange said WikiLeaks aided Snowden in his asylum applications and is paying for his travels.
The Ecuadorian government is "analyzing" Snowden's asylum request "with a lot of responsibility," Patino earlier told reporters in Hanoi, Vietnam.
"It has to do with the freedom of expression, with the security of citizens around the world, and therefore we have to analyze it deeply," Patino said.
U.S. warns China
Hong Kong's decision to let Snowden leave dealt efforts to build trust between the United States and China a "serious setback," Carney said Monday.
Hong Kong, a semi-autonomous Chinese territory, allowed Snowden to leave Sunday after declining to act on a U.S. request for a provisional arrest warrant, saying it needed more information.
Without that information, the Hong Kong government said, it had no reason to stop him from getting on the plane to Moscow.
Although Assange said Monday that Snowden traveled out of Hong Kong on refugee papers issued by Ecuador, Carney said U.S. officials had told Hong Kong authorities that Snowden's passport had been revoked "in plenty of time to have prohibited travel."
"We are just not buying that this was a technical decision by a Hong Kong immigration official," Carney said Monday. "This was a deliberate choice by the government to release a fugitive despite a valid arrest warrant, and that decision unquestionably has a negative impact on the U.S.-China relationship."
Carney declined to speculate what impact the decision could have on U.S.-China relations, but said U.S. officials are making their displeasure known "very directly."
The surveillance controversy
Snowden has acknowledged that he leaked classified documents about the National Security Agency's surveillance programs to the Guardian newspaper in Britain and to The Washington Post. The documents revealed the existence of programs that collect records of domestic telephone calls in the United States and monitor the Internet activity of overseas residents.
Snowden gave up a comfortable life "in order to bring to light what he believed was serious wrongdoing on the part of our political officials," said Glenn Greenwald, the Guardian columnist who co-authored the stories. "And he's now at best going to spend the rest of his life on the run from the most powerful government on Earth."
The disclosures shook the U.S. intelligence community and raised questions about whether the NSA is eroding American civil liberties.
Snowden told the Guardian that he exposed the surveillance programs because they pose a threat to democracy, but administration officials said the programs are vital to preventing terrorist attacks and are overseen by all three branches of government.
"We have not in a single case had a place where a government official engaged in willful effort to circumvent or violate the law. Zero times have we done that," Gen. Keith Alexander, the NSA's director, said on ABC's "This Week."
Snowden was a Hawaii-based computer network administrator for Booz Allen Hamilton, an NSA contractor. Alexander said Snowden "betrayed the trust and confidence we had in him" and is "not acting, in my opinion, with noble intent."
Greenwald said Snowden has been extremely judicious about what he has revealed.
"I know that he has in his possession thousands of documents which if published would impose crippling damage on the United States' surveillance capabilities and systems around the world. He has never done any of that," Greenwald told CNN.
An online petition calling on the White House to pardon Snowden passed the key threshold of 100,000 signatures over the weekend and had more than 110,000 early Monday.
The petition describes Snowden as "a national hero."
The White House says it will respond to any petition on its site that gathers more than 100,000 signatures in 30 days.
CNN's Alison Harding, Phil Black, Matt Smith, Catherine E. Shoichet, Jill Dougherty, Carol Cratty, Nic Robertson and Alla Eshchenko contributed to this report.