Before his plea bargain agreement, Tappin had denied attempting to sell batteries for surface-to-air missiles which were to be shipped from the US to Tehran via the Netherlands.
He was originally thought to have faced up to 35 years in jail if found guilty.
His guilty plea, to one count of the indictment, calls for a 33-month sentence which prosecutors have said they will not oppose him serving back in the UK.
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The Police Federation chairman said officers were often "letting someone off with a warning and hoping for the best".
A total of 21 are also injured by a blaze which ripped through the upmarket 22-storey hotel on the Black Sea coast.
A look ahead to the forecast for today across the UK.