LONDON — Trucks parked along freeways or stuck in gridlocked ports. Food disappearing from supermarket shelves and stocks of medicines under strain. The military on standby, ready to step in to avert crisis.

For a British public that has often tuned out from the mind-numbing complexities of Britain’s withdrawal from the European Union, recent government statements, amplified by raucous newspaper headlines, have finally become comprehensible — and alarming.

For days, talk has swirled about government preparations for a disruptive departure from the European Union without any agreement — a scenario that could mean new border checks, log-jammed ports, marooned trucks, and food, drugs and other essential supplies drying up.

The speculation was prompted by a government promise to prepare for all eventualities, including the extreme one of a “no deal” departure from the European Union, or Brexit. But even before the first of around 70 official “no deal” warning documents for businesses and consumers was published, they had — through the filter of the British news media — started to sound ominously reminiscent of rationing and other preparations during World War II.