The US Government has taken steps to end a labour dispute which has paralysed ports on the west coast for the past week. BBC News Online explains why an old-fashioned row over pay and working conditions sent ripples of alarm throughout corporate America.

It's just another spat between bosses and workers. Why is everyone so worried - and why did the government step in?

Because the dock workers at the centre of the dispute effectively control the shipping of physical goods to and from the west coast of the US.

All 29 international sea ports on the west coast had been paralysed for more than a week, effectively suspending the $300bn-a-year flow of goods between the US and Asia - probably the world's busiest and most lucrative trade route.

Economists estimate that the strike has cost the US about $1bn a day so far. They say that this could have risen to about $2.4bn a day this week as more companies resort to air freight, which costs up to ten times more than shipping.

When the stakes are this high, and there's a very close-run election less than a month away, it's little surprise that the government is taking an interest.

The 1947 Taft-Hartley Act, as it's known, allows the President - as long as he gets a judge's say-so - to force the two sides in a labour dispute back to work for up to 80 days if the row presents a threat to the "national health or safety".

Richard Nixon, in 1971, was the last incumbent to use these powers in a dock dispute, and few have disputed the decision this time around.

The 200-odd ships sitting laden and idle off the western seaboard of the US can now start offloading their cargoes.

Who was most affected?

Some Asian car companies scaled back production and laid off jobs at their US factories, while the West Coast-based technology giants Microsoft and Intel both said they were worried about the impact of the stoppage.

There were fears the dispute - which comes in the run-up to the all-important Christmas season, when US imports of toys and consumer electronics reach their peak - could have also hurt the economies of export-oriented Asian nations such as China, Japan, South Korea and Taiwan.

All of this came at the worst possible time for the global economy, which many analysts believe is already teetering on the edge of recession.

So I suppose the row that started the whole stoppage is settled now?

Far from it. If anything, the rhetoric has stepped up a notch or two.

At the heart of the argument is a good old-fashioned row over pay and conditions, and resolving these has never been easy.

At issue are the pension and benefit packages written into the dock workers' employment contracts, which are up for renewal after expiring in July.

Dock workers are also protesting against plans to install new hi-tech equipment, which they fear will lead to job losses.

The International Longshore and Warehouse Union (ILWU) is therefore seeking guarantees that if job titles and so on are changed, the new positions will be unionised as well.

And it's gone so far as to accuse the White House of colluding with the bosses' lobby, the Pacific Maritime Association (PMA), to weaken the workers' bargaining position in negotiations which have been deadlocked for five months.

"We've got a new dock boss down here, and his name is George Bush," one local union president said.

Who's to blame for the closure of ports?

The ports shutdown was actually precipitated by the PMA, which last week locked workers out of the docks, accusing them of adopting an illegal work-to-rule strategy aimed at slowing down freight transit times.

It said it would not readmit them until the ILWU agrees to roll over the lapsed employment contracts while a new deal is discussed.

Bosses and workers held a marathon 15-hour meeting on Saturday, but observers said an agreement was still some way off.

The head of the US' industrial dispute conciliation service said after the talks that the issues separating the two sides are "ones of principle, and therefore very difficult to resolve".

And more trouble could be on the way despite the return to work.

The dockers say that because of the scale of the backlog - and their pre-existing worries about safety - they will "work safe", the term for following every regulation to the letter.

That could put them in contempt of court, although the judge in question said he hasn't decided whether the move would constitute a breach of his order to work at a "normal and reasonable rate".