NEW YORK (CNN/Money) - Labor and management at U.S. West Coast ports returned to the table Monday evening, but verbal attacks between the two sides suggested that no end is in sight for the work stoppage that has essentially closed the ports since Friday evening.

The work stoppage has the potential to cost the already struggling U.S. economy about $1 billion a day and essentially choke off trade between the United States and Asia. Retailers are in the midst of importing goods for the holiday shopping season and some manufacturing plants could have operations halted as soon as this week due to the lack of parts needed to complete their products.

The Pacific Maritime Association, representing major shipping lines and port terminal operators, locked out dockworkers indefinitely at 29 West Coast ports, and the International Longshore and Warehouse Union both vowed not to give in on their positions Monday evening, even as negotiators met face to face for the first time since Friday afternoon.

Management said the talks Monday lasted about 90 minutes and did not touch on the most contentious issue in the negotiations -- PMA's demand for greater use of technology.

"The union told us that technology is off the table," said a statement by PMA negotiator Tom Edwards. "We have already told the union that we would provide substantial enhancements to the pension package, and we will continue to discuss the issue. Technology cannot be taken off the table. It is the core issue in these talks. We must modernize our terminals and bring our waterfront into the 21st century. The union can't turn back the clock."

The union said earlier in the day that it would not give into management demands.

"The ILWU will not be intimidated," said union International President James Spinosa in a speech Monday. "The union will continue to resist any move by the employers that continues to erode our work or move work away from us."

A labor dispute shuts down sea ports along the U.S. West Coast. CNN's Casey Wian reports. Play video (QuickTime, Real or Windows Media)

Management is seeking to have data from outside sources, such as shipping lines and their customers, downloaded into PMA computers rather than having it reentered manually by ILWU clerks. Management says that it will provide job guarantees for current ILWU members as well as improved benefits to win that greater use of technology. The union is demanding jurisdiction over other work and staffing level guarantees to allow the use of the technology, but PMA has rejected that offer as unworkable.

The PMA locked out the union for 38 hours starting Friday evening, then reopened the ports Sunday morning. But management charged that the union, which represents 10,500 dock workers, then continued a series of work slowdowns Sunday, so PMA resumed the lockout Sunday evening.

Management said it will not end the lockout until the union agrees to a new contract or agrees to reinstitute the expired contract so that management would have an arbitration process to combat alleged work slowdowns.

President Bush has the power to order the two sides back to work for 80 days, but administration officials would not divulge their plans for dealing with the crisis Monday.

"If it goes on for even a short period of time, it's a problem for the economy," White House spokesman Ari Fleischer told reporters.

Unlike airline or railroad labor disputes, Bush does not have the power to move to impose terms of a labor agreement on the two sides.

Nineteen cargo ships were sitting idle at dockside at the Port of Los Angeles, with nine more ships being held outside the port, according to port spokeswoman Theresa Adams Lopez.

"We have no idea how long this could take," Lopez said.

The Federal Mediation and Conciliation Service (FMCS) has asked both sides to meet in Washington, D.C., Thursday to talk to mediators. The PMA has agreed to that date, but the union has not yet said whether or not it will agree to the mediation.

A prolonged shutdown, coming during the pre-holiday shipping period, also could hurt the shipping companies that transport goods to the ports. It is estimated by major retailers that every one-day delay at the port can back up goods for about a week.

"The longer this goes on, the worse it's going to be for shippers," said Ed Rastatter, director of policy development and research at the National Industrial Transportation League. "They're still getting in holiday cargoes and freight. The longer they delay, the worse it's going to be to dig out from the mess."

On the other hand, Port of Long Beach spokesman Fausto Capobianco said shipping volume at his port, the nation's second-busiest, had been unusually high in recent months, which could be a sign that retailers anticipated a work stoppage and had already ordered their holiday goods.

"Those large shipments that were coming in will probably keep shopkeepers going OK for the time being," though a shortage of goods could make them more expensive for consumers, Capobianco said.

ILWU members are among the best-paid blue-collar workers in the nation. The longshoremen earned an average of $82,895 last year, while clerks earned an average of $118,844 and foremen, who are members of the union, earned an average of $157,352.