What have we learned from the Pentagon leaks?

The Pentagon has said the leaks is one of the most serious security breaches in years. Credit: AP

The classified Pentagon documents leaked online have shed new light on how the US intelligence service operates and how much they know about the war in Ukraine.

The US government has said the leak is one of the most serious in years and has arrested Air National Guardsman Jack Teixeira in relation to the case.The documents first started appearing on the online chat programme Discord in March before they spread to 4Chan and were noticed by journalists and Russian war monitors.

The US has refused to acknowledge if the documents are real but several American news organisations have been told off the record they are mostly authentic, although some appear to have been tampered with.

Just how many documents were leaked is not known, but here is a list of some of the things we have learned so far.

In-depth detail on the war in Ukraine

Although the world has been closely watching the war in Ukraine, details on precise battle plans, troop movements and accurate casualty numbers have been closely guarded on both sides.

The leaked documents contain some of the US Intelligence services' best estimates on what the situation is on the ground.

The leaks revealed suspected casualty numbers from the war in Ukraine. Credit: AP

The documents make clear that their findings probably aren't accurate, with only the Russian and Ukrainian governments knowing the true picture.

Both the US and Ukrainian governments have also said some of the documents are fake, have been fabricated or are already out of date.

The documents revealed Ukraine's air defence systems were likely to run out of ammo in early April without rapid resupply.

A document dated March 23 also said a small number of Western special forces were operating in Ukraine, including 50 British personnel.

One document seen by the Washington Post shows the US intelligence services doubting whether Ukraine had the manpower and resources necessary to achieve anything other than "modest territorial gains" during a counteroffensive.

Another document, a picture of a slide from a presentation, shows the US's estimate of casualties suffered by both sides.

They suggest Russia has suffered 223,000 soldiers killed or wounded, with Ukraine sustaining around 131,000 casualties.

The leaks also show infighting between Russian agencies over how to count the war dead, with the Russian military preferring to only count army losses, leaving out mercenaries.

South Korea's uncertainty about supplying Ukraine with ammunition

One of the biggest diplomatic headaches caused by the leaks is the possible indication the US spied on its ally South Korea and learned about their indecision over backing Ukraine.

The leaked documents contain purportedly private conversations between senior South Korean officials about Ukraine.

They show South Korean military officials unsure over whether to agree to a US request to supply Ukraine with artillery shells.

The US has been trying to encourage its allies to supply weapons to Ukraine. Credit: AP

South Korea, a growing arms exporter, has a policy of not supplying weapons to countries at war.

It has not provided arms directly to Ukraine, although it has shipped humanitarian aid and joined economic sanctions against Russia.

South Korea has also sold shells and ammunition to Nato countries to refill stocks depleted by supplying them to Ukraine.

The leaks have put both countries in a tight spot ahead of a state visit to the US by President Yoon Suk Yeol scheduled to happen later this month.

The South Korean government has said several of the documents were fabricated and the US has declined to acknowledge if they were authentic.

Egypt planned to secretly sell rockets to Russia

In another document seen by the Washington Post, the US believes Egypt had planned to secretly sell 40,000 rockets to Russia.

It is not clear if Egypt went ahead with the plan.

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The Post said President Abdul Fatah al-Sisi told his government to keep the plan secret to "avoid problems with the West."The document also said Egypt wanted to supply the rockets in order to repay some unspecified help Russia had previously provided.Russian intelligence operatives in the United Arab Emirates

The leaked documents also show US spies caught Russian intelligence officers boasting that they had convinced the UAE "to work together against US and UK intelligence agencies."

The US has had growing concerns that the UAE was allowing Russia and Russians to thwart sanctions imposed over the invasion of Ukraine.

The document says that Russian spies claimed "UAE security service officials and Russia had agreed to work together against US and UK Intelligence agencies, according to newly acquired signals intelligence."

The UAE and US have said some of the documents were fake.