Alexandria, Virginia (CNN) George Nader, a key witness in the Russia investigation, pleaded guilty Monday to two sex crimes involving minors.

During an hour-long court hearing, Nader admitted that he brought an underage boy to the US for sex, and that he possessed child pornography depicting sexual abuse of toddlers.

Both of these crimes occurred years before Nader worked his way into President Donald Trump's orbit after the 2016 election, when he served as an informal foreign policy adviser and attended high-level meetings.

Nader, 60, will be sentenced in April. He has been in jail since June, after a judge ruled that he was too dangerous to be released on bail, and wore a green jail uniform during the hearing in Monday. The child pornography charge carries a minimum sentence of 10 years in prison. Under the terms of a plea deal, the Justice Department agreed to recommend that Nader only receive that minimum 10-year term, though Nader's sentence will ultimately be decided by federal Judge Leonie Brinkema.

A Middle East specialist with connections to powerful figures throughout the region, Nader became an informal foreign policy adviser to the Trump transition after the 2016 election. He attended meetings during the presidential transition with Trump's son-in-law Jared Kushner, former chief strategist Steve Bannon and former national security adviser Michael Flynn.

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