‘It’s all happening again.’ The supply chain is under strain.

Stephanie Loomis had hoped the chaos surrounding the global supply chain was dying down. Blockage of shipping traffic outside ports. Multiplied costs of movement of goods. As a result of the lack of goods. All this seemed like an unpleasant memory limited to the Covid-19 pandemic.

There is no such luck.

As Head of Ocean Freight for the Americas at Rhenus Logistics, a Germany-based company, Ms. Loomis spends her days negotiating with international shipping carriers on behalf of clients moving products and parts around the globe. Over the past few months, it has seen cargo prices rise as a series of concerns rocked the seas.

Late last year, Houthi rebels in Yemen began firing on ships entering the Red Sea en route to the Suez Canal, a vital artery for ships moving between Asia, Europe and the East Coast of the United States. This caused ships to avoid the waterway, instead taking the long route around Africa, extending their journeys by up to two weeks.

Then, a major drought in Central America lowered water levels in the Panama Canal, forcing authorities to limit the number of ships passing through that canal crucial to international trade.

In recent weeks, dockworkers have threatened to strike on the East and Gulf coasts of the United States, while workers at German ports have stopped shifts in search of better wages. Rail workers in Canada are poised to walk off the job, jeopardizing freight moving across North America and threatening stocks at major ports like Vancouver, British Columbia.

Intensifying shipping turmoil is prompting shippers to raise rates, raising the specter of water blockages that could again threaten retailers with product shortages during the holiday shopping season. The shutdown could also worsen inflation, a source of economic anxiety fueling the US presidential election.

If the pandemic’s supply chain concerns proved anything, it was this: Problems in any country tend to spread widely.

A container full of chemicals that arrives late at its destination portends production delays for factories waiting for these ingredients. Ships stuck in ports wreak havoc on freight traffic, clogging warehouses and putting pressure on the trucking and rail industries.

“I’m lovingly calling the market now ‘Covid junior’ because in many ways we’re back to where we were during the pandemic,” said Ms. Loomis. “It’s all happening again.”

Since October, the cost of moving a 40-foot shipping container from China to Europe has risen to about $7,000, from an average of about $1,200, according to data compiled by Xeneta, a Norway-based cargo analytics company. That’s well below the peak of $15,000 reached in late 2021, when supply chain disruptions were at their worst, but it’s about five times the prices that prevailed in the years leading up to the pandemic.

Tariffs for shipping goods across the Pacific have been multiplied by a similar amount. It now costs over $6,700 to ship a 40-foot container from Shanghai to Los Angeles, and nearly $8,000 for Shanghai to New York. As recently as December, those costs were close to $2,000.

“We haven’t seen the peak yet,” said Peter Sand, principal analyst at Xeneta.

Importers who rely on shipping complain about the return of another source of worry they suffered during the pandemic: shippers often cancel confirmed bookings, while demanding special handling fees and premium service fees as a requirement to get containers on board.

“Everything is a struggle to get containers,” said David Reich, whose Chicago company, MSRF, assembles gift baskets for Walmart and other giant chains. “It’s frustrating.”

Alarmed by growing threats to shipping, Mr. Reich is accelerating plans to stockpile goods for the holiday season. It is pressuring its suppliers in China to pack its food items faster, anticipating shipping delays.

Mr. Reich has contracts with two ocean carriers to move four containers a week from China to Chicago at prices under $5,000. However, he was recently informed that shippers were imposing “peak season surcharges” that would add up to $2,400 per container, he said.

And even at those prices, carriers often say they don’t have space on their ships, he complained. He fears he will have to use the reserve in the so-called spot market, where prices fluctuate, with rates now reaching $8,000.

In an emailed statement, the World Shipping Council, an industry trade association, said “spot rates reflect supply and demand in a competitive, global market and most container traffic moves at rates negotiated through long-term contracts.” .

Experts challenge this assertion, noting that container shipping is characterized by a lack of competition on major routes, allowing carriers to raise prices significantly when the system is strained.

Three major carrier alliances control 95 percent of container traffic between Asia and Europe and more than 90 percent between Asia and the East Coast of the United States, according to the International Shipping Forum, an intergovernmental organization in Paris with 69 member countries, including China . and the United States.

During the worst disruptions of the pandemic, when extreme delays and product shortages prompted sellers to pay shippers up to $28,000 to move single containers across the Pacific, the industry posted record profits.

New Balance, the athletic shoe brand, is partially offset by its reliance on factories in the United States, as well as its contracts with companies that have prices. However, in some cases, the company has been forced to pay spot market rates that have risen sharply, “similar to the peak years of the pandemic — more than 40 percent month over month,” said Dave Wheeler, chief operating officer. an email.

Carriers have canceled some scheduled sailings, reducing capacity, Mr. Wheeler added. “We see a storm brewing in 2024 for reliability and price risks.”

The most immediate cause of the recent rise in ship prices is the targeting of ships by the Houthis, who are acting in support of Palestinians under attack by Israeli forces.

That threat appears to be escalating, as Iran-backed Houthi rebels increase the frequency of their attacks, supplementing missile strikes with naval drones — essentially remote-controlled water boats loaded with explosives.

In recent weeks, such attacks have sunk two ships, including a Greek ship carrying coal.

With container traffic through the Suez Canal falling to a tenth of its usual flow, most ships moving between Asia and Europe now circumnavigate Africa, requiring more fuel to be burned.

At the same time, carriers have concentrated their fleets on the most profitable routes, those connecting destinations such as Shanghai and the Dutch port of Rotterdam, Europe’s busiest. This has forced cargo destined for other countries to stop for loading and reloading at major hubs known as shipping ports.

The largest such ports, including Singapore and Sri Lanka’s capital, Colombo, are now overwhelmed with inbound ships. Ships must wait at anchor for as long as a week before pulling into ports.

Given the disruptions and additional costs, an increase in shipping charges is inevitable. But industry insiders argue that carriers are raising prices beyond recouping their additional costs.

“Carriers learned a very valuable lesson during the pandemic,” said Ms. Loomis. “They will manipulate capacity and increase freight rates.”

The biggest concern is that floating blockages could become a self-fulfilling prophecy. As importers absorb the reality of rising shipping prices and port congestion, they are ordering early. This could result in an increase in inbound cargo at major ports such as Los Angeles, Newark and Savannah, Ga., exceeding truck, rail and warehouse capacity.

The prospect of a rail strike in Canada is causing freight destined for Vancouver to be diverted to Southern California, the scene of the worst traffic jams during the pandemic disruptions.

In Tennessee, F9 Brands, an importer of cabinetry and flooring products, has increased its orders in the face of longer delivery times, said Jason Delves, the company’s chief executive.

The company brings cabinets from factories in Vietnam, Thailand and Malaysia to the Port of Savannah, and then to its warehouses in Tennessee via rail and truck. Typically, this trip takes six weeks. “Now, you’re increasing that to more than eight weeks,” said Mr. Delves.

Adding to the concern is the reality that no one knows how long the final outage will last, or how it will happen.

Panama Canal restrictions have largely been lifted as the rainy season replenishes water supplies. But climate change is increasing the risks of future droughts.

The consequences of the pandemic were quite difficult to understand, with major miscalculations on the impacts on demand for factory goods. But everyone understood that pandemics eventually end.

The Houthi attacks and the effects on the Suez Canal, on the other hand, involve large geopolitical variables that make prediction difficult.

“It is a very complex situation and it seems open,” said Mr. Sand, Xeneta analyst. “There is no clear solution in sight.”