The NSA whistleblower Edward Snowden has expressed confidence that international pressure will force the United States to drop its prosecution of his case, in a letter revealed on Friday.

Snowden reflected on his legal status in a letter that was handed in person on Thursday to a member of the German parliament, which is to hold a debate on NSA spying later this month.

"I hope that when the difficulties of this humanitarian situation have been resolved, I will be able to cooperate in the responsible finding of fact regarding reports in the media, particularly in regard to the truth and authenticity of documents," Snowden wrote in the letter, which was addressed to the German government.

Outrage over American spying has grown in Germany since Der Spiegel magazine reported last Saturday that the NSA has been monitoring chancellor Angela Merkel's mobile phone since 2002. Impassioned opposition to US surveillance has also emerged in Brazil, France and elsewhere – including the United States.

“I am heartened by the response to my act of political expression, in both the United States and beyond,” Snowden wrote, later asserting that "the outcome of my effort has been demonstrably positive".

The US, however, "continues to treat dissent as defection" and "seeks to criminalize political speech with felony charges that provide no defense", he wrote.

Hans-Christian Stroebele presents Edward Snowden with the Whistleblower Award 2013. Photograph: Irina Oho/HO/EPA Photograph: IRINA OHO / HO/EPA

Snowden was charged in June with unauthorized communication of national defense information and willful communication of classified communications intelligence information to an unauthorized person. The offenses fall under the US Espionage Act and carry penalties of fines and up to 10 years in prison. Snowden also has been charged with theft of government property, and could face further charges in the future.

A decision not to bring charges against Snowden would require the Obama administration to change its spots. Under President Barack Obama, the department of justice has used the 1917 Espionage Act to bring felony charges against government employees or contractors eight times – compared with three such prosecutions previously ever. A report by the Committee to Protect Journalists found that Obama has pursued the most aggressive "war on leaks" since the famously paranoid Nixon administration.

"I look forward to speaking with you in your country when the situation is resolved, and thank you for your efforts in upholding the international laws that protect us all," Snowden's letter concluded.