The U.S. air national guardsman suspected of leaking a trove of classified intelligence documents pertaining to national defense was charged on two counts on Friday under the Espionage Act for allegedly posting the sensitive material online.

Teixeira, 21, will remain detained through the next court hearing on Wednesday.

A trove of leaked Pentagon documents, from late February to early March but found on social media sites in recent days, has again illustrated the broad reach of U.S. spy agencies, including into the capitals of friendly countries such as Egypt, South Korea, Ukraine and the United Arab Emirates, The New York Times reported on Thursday.

"Though the documents mainly focus on the war in Ukraine, they include CIA intelligence briefs describing conversations and plans at senior levels of government in those countries, in several cases attributed to 'signals intelligence,' or electronic eavesdropping," said the report.

"They have served to remind the world of America's talent for spying – and the diplomatic blowups and reputational damage stemming from the leaks," it added.

"The last time a trove of leaked documents exposed U.S. spying operations around the world, the reaction from allied governments was swift and severe," noted the report.

In the wake of the leak of documents by Edward Snowden in 2013, thousands of people protested in the streets in Berlin, the CIA station chief was expelled, and the German chancellor told the American president that "spying on friends is not acceptable." In Paris, the U.S. ambassador was summoned for a dressing-down. Brazil's president angrily canceled a state visit to Washington, added the report.

U.S. spying on UN chief

The BBC pointed out that the latest leaked documents also suggest the U.S. has been closely monitoring UN Secretary-General Antonio Guterres and his deputy, noting that UN officials are obviously unhappy with the United States.

"He (Guterres)'s not surprised by the fact that people are spying on him and listening in on his private conversations. What is surprising is the malfeasance or incompetence that allows for such private conversations to be distorted and become public," Guterres' spokesman, Stephane Dujarric, was quoted as saying.

Guterres urged all countries to respect the communication security of the UN, when asked about the leaked documents involving the U.S. surveillance of him.

In 2013, the documents Snowden leaked revealed that a new age of spying had begun after September 2001, The New York Times reported. It became clear that the United States, driven by fears of foreign terrorism and empowered by technological advances, had created a sophisticated network of global surveillance that was scooping up vast amounts of data from millions of emails and phone calls around the world.

The Guardian also reported in 2013 that as many as 35 leaders were on the U.S. National Security Agency surveillance list, including then United Nations Secretary-General Ban Ki-moon.

Polling by the Pew Research Center later found that those disclosures had harmed the United States' public image. A Pew survey of 44 countries found widespread opposition to U.S. covert surveillance, with more than 73 percent of respondents saying they opposed spying on their leaders.

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(With input from agencies)