The closure, due to take place in September, is expected to affect about 300 staff. Iceland has offered to relocate a similar number to its distribution centre in Warrington.
The 115 drivers and 175 warehouse staff began the one-day strike at midnight on Thursday. As of midnight tonight, they will adopt a work-to-rule policy.
A union spokesman said Iceland had taken the 'unnecessary' and 'very provocative' action of employing security staff at the picket lines. The union has now involved the police in respect to 'intimidation' on the part of Iceland.
Members of the Transport and General Workers Union (T&G) voted for strike action after Iceland refused its cost-saving proposals, which it claimed would have saved the retailer its target of£2 million.
T&G leader Andy Richards said: 'Despite our local negotiator's proposal, Iceland has decided to go ahead with the plan. Frankly, we believe this was their intention all along. The company has been disingenuous from the start and simply wanted to blame the union for its own failings. They have even refused to agree redundancy terms with us for the people they are throwing out of work.'
Iceland chief executive Malcolm Walker said: 'We have taken the decision to close Deeside with considerable reluctance, as the result of our failure to achieve agreement with the trade union on wages and working conditions that would have made it viable. Deeside is one of four Iceland depots in the UK and is by far the least efficient and most expensive to operate.'
The union said it was considering further strike action next week if its demands are not met.