NEW YORK, April 10. /TASS/. Kiev has reconsidered its military plans after classified documents of the Pentagon and the US intelligence community were leaked on the Internet, a source close to Ukrainian President Vladimir Zelensky told CNN.

According to the TV channel, Ukraine has already altered "some of its military plans" because of the leaked documents, which also gave estimates of the Kiev regime’s combat potential. CNN did not dwell on the changes or their scale.

The documents expose the extent of US spying on its allies and foes, CNN said. A number of US officials fear the release could compromise foreign relationships.

Earlier, Pentagon deputy press secretary Sabrina Singh said that the US Defense Department was assessing the validity of the allegedly classified documents. Washington is "assessing the impact those photographed documents could have on US national security" and on the country’s "allies and partners" through an interagency effort, Singh said.

The documents which appeared on the Internet may have been doctored, Reuters said. The documents reveal US and NATO plans to build up Ukrainian forces before a counteroffensive. An array of materials revealing information about schedules for the supply of weapons, the number of troops and battalions was posted on Twitter and Telegram. The leak is seen as one of the biggest breaches of secret data since more than 700,000 documents, videos and diplomatic cables were released through WikiLeaks in 2013.