Prime Minister Benjamin Netanyahu spoke with US President Donald Trump before a major Israeli intelligence operation in Iran, in order to secure American support if the mission were to go awry, Israeli television reported Tuesday.

In April, Netanyahu revealed a trove of documents he said proved that Iran had lied about its nuclear program. He said that the Mossad intelligence agency had spirited the documents out of a warehouse in the the Iranian capital, Tehran, and called the haul was one of the “greatest achievements” of Israeli intelligence.

Netanyahu discussed the mission with Trump when the two met in Davos last January, according to Hadashot TV news, with the prime minister seeking US assistance in case the Israeli operatives had to be rescued during the mission.

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It was not clear from the report how Trump responded to the request or whether it was the first time he heard about the operation. The New York Times previously reported that Trump was informed of the operation by Mossad chief Yossi Cohen during a visit to Washington in January.

The report did not say how Trump responded to the request.

The network also reported that the extraction of the Mossad agents was far more complicated than previously reported, but did not provide any details.

Though Netanyahu gave few details of the operation during his April speech, a senior Israeli official told The New York Times that the Mossad had discovered the warehouse in February 2016, and had the building under surveillance since then.

The operatives broke into the building one night last January, removed the original documents and smuggled them back to Israel the same night, the official said, according to the paper.

The official said the delay in making the material public was due to the time it took to analyze the documents, the vast majority of which were in Persian.

Netanyahu described the archive as looking like a “dilapidated warehouse” in the Shorabad District in southern Tehran.

“This is where they kept the atomic archives. Right here. Few Iranians knew where it was, very few, and also a few Israelis,” Netanyahu said.

“Now, from the outside, this was an innocent looking compound. It looks like a dilapidated warehouse. But from the inside, it contained Iran’s secret atomic archives locked in massive files,” he said.

Netanyahu showed a picture of long rows of safes and said that the agents managed to bring back “half a ton of the material” consisting of 55,000 pages and another 55,000 files on 183 CDs.

The cache, he said, contained “incriminating documents, incriminating charts, incriminating presentations, incriminating blueprints, incriminating photos, incriminating videos and more.

“We’ve shared this material with the United States, and the United States can vouch for its authenticity,” he said of the information.