Top U.S. diplomat Antony Blinken and defense chief Lloyd Austin spoke with their Ukrainian counterparts on Tuesday as Washington seeks to reassure its allies after dozens of classified intelligence documents, which, The Washington Post reported, exposed how the U.S. spies on friends and foes alike, appeared online.

"We have engaged with allies and partners at high levels over the past days, including to reassure them about our own commitment to safeguarding intelligence," Blinken told a news conference on Tuesday.

Blinken said he had spoken with his Ukrainian counterpart Dmytro Kuleba and "reaffirmed our enduring support for Ukraine and for its efforts to defend its territorial integrity, its sovereignty, its independence."

"The documents, which appear to have come at least in part from the Pentagon and are marked as highly classified, offer tactical information about the war in Ukraine, including the country's combat capabilities," according to a report from The Washington Post.

"The series of detailed briefings and summaries open a rare window on the inner workings of American espionage," said the report. Among other secrets, they appear to reveal where the CIA has recruited human agents privy to the closed-door conversations of world leaders; eavesdropping that shows a Russian mercenary outfit tried to acquire weapons from a NATO ally to use against Ukraine; and what kinds of satellite imagery the United States uses to track Russian forces, including an advanced technology that appears barely, if ever, to have been publicly identified.

Many of the documents seem to have been prepared over the winter for senior military officials, but were also available to other U.S. personnel and contract employees with the requisite security clearances, the report said, citing one defense official.

Other documents include analysis from U.S. intelligence agencies about Russia and several other countries, all based on information gleaned from classified sources, according to the report.

Senior Pentagon leadership restricted the flow of intelligence on Friday in response to the revelations, the Post quoted U.S. officials as saying, adding that one described the clampdown as unusually strict and said it revealed a high level of panic among Pentagon leadership.

(With input from agencies)