Considering the scope of US spying on important allies and the infiltration of Russian targets, the leak of highly classified Pentagon documents has alarmed US officials who fear it could harm crucial sources and international ties. 

Recently leaked highly classified documents from the Pentagon have given insight into how the US spies on allies and foes, causing concern among US officials over the potential damage to important foreign relationships and sensitive sources. Some of the documents reveal the extent of US eavesdropping on key allies including South Korea, Israel, and Ukraine, while others expose the degree to which the US has penetrated the Russian Ministry of Defense and mercenary organization Wagner Group. The leak has already caused Ukraine to alter military plans, and US allies are carrying out damage assessments to determine if their own sources and methods have been compromised. The Pentagon has initiated an interagency effort to assess the impact of the leak, while the Joint Staff is examining its distribution lists for such highly sensitive documents. The Justice Department has also launched an investigation into the source of the leak. 

Source: https://www.cnn.com/2023/04/09/politics/pentagon-leaked-documents-us-spying-allies-foes/index.html