Edward Snowden is calling for international help to persuade the U.S. to drop its espionage charges against him, according to a letter a German lawmaker released Friday after he met the American in Moscow.

U.S. Secretary of State John Kerry, meanwhile, has conceded that some of the NSA’s spying has reached too far and will be stopped.

Snowden said he would like to testify before Congress about National Security Agency surveillance and may be willing to help German officials investigate alleged U.S. spying in Germany, Hans-Christian Stroebele, a lawmaker with Germany’s opposition Greens, told a press conference.

But Snowden indicated in the letter that neither would happen unless the U.S. dropped its espionage charges — a policy shift the Obama administration has given no indication it would make.

Stroebele’s Thursday meeting with Snowden took place a week after explosive allegations from the Der Spiegel news magazine that the NSA monitored Chancellor Angela Merkel’s cellphone prompted her to complain personally to President Barack Obama. The alleged spying has produced the most serious diplomatic tensions between the two allies since Germany opposed the U.S.-led invasion of Iraq in 2003.

Germany’s top security official, meanwhile, said he would like to arrange for German authorities to talk to Snowden about those allegations and other U.S. surveillance operations that have enraged Europeans.

Snowden has said he no longer has the NSA materials but his knowledge of U.S. spying efforts could be seen as invaluable by other nations.

“He pointed out that he was active in the U.S. secret services, the NSA and CIA, not just as an administrator or something like that who had access to computers, but also … participated in operations,” Stroebele said of Snowden.

“He noted that he knows a lot about the inner structure … that means he can, above all, interpret and explain all the documents. … He could explain authentically only as an NSA man could. That means he is a significant witness for Germany too.”

In his one-page typed letter, written in English and bearing signatures that Stroebele said were his own and Snowden’s, Snowden complained that the U.S. government “continues to treat dissent as defection, and seeks to criminalize political speech with felony charges that provide no defense.”

“I am confident that with the support of the international community, the government of the United States will abandon this harmful behavior,” Snowden wrote.

But he indicated he wouldn’t talk in Germany or elsewhere until “the situation is resolved.”

Stroebele said Snowden appeared healthy and cheerful during their meeting at an undisclosed location in Moscow. The German television network ARD, which accompanied Stroebele, said the Germans were taken to the meeting by unidentified “security officials” under “strict secrecy.”

“(Snowden) said that he would like most to lay the facts on the table before a committee of the U.S. Congress and explain them,” Stroebele said. The lawmaker, a prominent critic of the NSA’s alleged activities, said the 30-year-old “did not present himself to me as anti-American or anything like that — quite the contrary.”

In a video link to an open government conference in London, Kerry said Thursday that because of modern technology, some of the NSA activities have been happening on “automatic pilot” without the knowledge of Obama administration officials.

Kerry said ongoing reviews of U.S. surveillance will ensure that technology is not being abused.

“The president and I have learned of some things that have been happening in many ways on an automatic pilot, because the technology is there,” Kerry said. “In some cases, some of these actions have reached too far and we are going to try to make sure it doesn’t happen in the future.”