The recent leak of a trove of apparent classified US documents poses "a very serious risk" to American national security, the Pentagon warned on Monday as the Biden administration continues to assess the disclosure's impact.

The documents "have the potential to spread disinformation," spokesperson Chris Meagher told reporters. The Pentagon continues to coordinate efforts to determine the full impact that these documents might have on US national security, he said, noting that "there's still a lot that we have to review and assess."
"We're being very careful, and watching where this is being promoted and amplified. And we're going to continue to coordinate efforts to determine the damage. That's something we're still looking into," he said.
The Defense Department is examining "how this type of information is distributed and to whom," added Meagher.
The Pentagon on Friday said it was investigating the unauthorized disclosure of the documents, which carry US Joint Chiefs of Staff seals and allegedly belong to the US and NATO. They were shared on social media, including Twitter and Telegram.
The Justice Department has separately opened a criminal investigation into the leak.
The Biden administration has repeatedly denied weighing in on their authenticity, but they include information about the course of the war in Ukraine, humanitarian aid provided by different countries and calendars for aid being delivered to Kyiv's forces.
They do not show specific times and places of war but contain factual information about the requirements of the Ukrainian army for the following weeks. On documents marked "top secret," there are details about the Ukrainian battalion locations and sizes, as well as total losses on both sides.
A document listing the Ukrainian military equipment and training process suggests that 12 battalions have been prepared, and nine were trained by NATO allies and the US. The same document reveals that six of the nine battalions will be ready by March 31 and the rest by April 30. The nine will need up to 250 tanks and 350 mechanized vehicles.
Some of the contents appear to be altered, particularly casualty tolls for both Ukrainian and Russian forces, which diverge from those publicly assessed by the US.
Apart from Ukraine, the scores of documents also include US intelligence on a variety of issues and nations, including South Korea and Israel.
National Security Council spokesperson John Kirby told reporters that US President Joe Biden was briefed on the leak late last week, adding that US officials "have been in touch with relevant allies and partners, given some of these disclosures over the last few days and we'll continue to have those conversations as appropriate."
The State Department added that the agency is "engaging with allies and partners at high levels over this, including to reassure them of our commitment to safeguarding intelligence and the fidelity of securing our partnerships."