To witness the buildup to a brewing trade war between the U.S. and China, look no farther than the Port Oakland, where shipping traffic has been heating up along with the rhetoric over President Trump’s tariffs.

On Thursday, the port reported that import volume reached a record high last month, possibly due to shippers rushing to beat import tariffs that kicked in this month.

The summer and fall are peak season for the port — third-busiest in California and fifth in the country — when most U.S. imports from Asia are shipped, and with the surging economy, shipping was expected to be strong.

But the port also said importers may have ordered aggressively in June ahead of tariffs imposed this month by the U.S. and China as the Trump administration ramps up an ongoing trade dispute.

Detailed numbers won’t be available for four to six weeks, said Port of Oakland spokesman Mike Zampa. “But analysts who look at the industry regularly tell us that importers may have been ordering more than usual this time of year to try and preempt the imposition of tariffs.”

The port said it handled the equivalent of 87,207 20-foot import containers in June, beating the previous monthly record of 84,835 containers set last July. June import volume was up 8.7 percent over June 2017, the port said. Total container volume in Oakland is up 2.3 percent so far this year, in line with a January port forecast projecting growth between 2 and 3 percent in 2018.

China was the port’s top trading partner in 2017, accounting for 49 percent of imports and 30 percent of exports, port spokesman Robert Bernardo said. Furniture and bedding accounted for 49 percent of all imports from China, with Costco Wholesale, Crate & Barrel and Outdoor Living the top importers. Wastepaper accounted for 54 percent of all exports to China, with American Chung Nam, Denison International, Cycle Link, Potential Industries and JC Horizon among top exporters.

Increased port business is good for the Bay Area economy. The Port of Oakland, which oversees the Oakland Seaport, Oakland International Airport and nearly 20 miles of waterfront including Jack London Square, supports more than 73,000 jobs in the region and nearly 827,000 jobs across the United States. More ships coming in means more jobs and work hours for longshoremen, warehouse workers, drivers and others.

But the question now is how will the tariff hikes impact future ship traffic from China: Port officials said it’s too soon to tell. They said the increases would have affected about $225 million of China imports had they been in place last year.

“There’s uncertainty over the international trade picture, so we’re taking a wait-and-see approach,” Port of Oakland Maritime Director John Driscoll said in a statement Thursday.

Export volume is down 1.8 percent through six months of 2018, and 4.7 percent in June, port officials said. The port attributed that to a strong U.S. dollar, which makes American goods costlier overseas.

The tariffs are part of an effort by President Donald Trump’s administration to pressure China over trade practices that have long vexed American businesses. Those include theft of intellectual property, forced transfer of American technology and cyber attacks the administration sees as unfair trade practices aimed at undermining America’s high-tech industry and economic leadership.

In late May, the administration announced plans for 25-percent tariffs on $50 billion worth of Chinese imports on industrial and transportation goods and components. Tariffs on $34 billion worth of those imports kicked in July 6, and levies on an additional $16 billion in goods will take effect in coming weeks.

But China has greeted the U.S. tariffs in kind with new levies on an equal value of American exports. Peter Morici, an economist and business professor at the University of Maryland, said those include soybeans, automotive products and bourbon whiskey aimed at hurting the economy in heartland states that are Trump’s support base.

The economic tit-for-tat could quickly escalate, with the Trump administration threatening to impose new 10-percent tariffs on $200 billion to $450 billion worth of Chinese goods that could include fish, chemicals and handbags.

Economists have been skeptical of the strategy.

“We have heard little of what the end game looks like other than boastful confidence that our targets will bend quickly,” Morici wrote Thursday. “And when quickly doesn’t happen, domestic political pressure could impose a harsh lesson on an overconfident Mr. Trump and thrust the United States into a humiliating and costly defeat.”

U.S. imports totaled $2.9 trillion last year and exports $2.35 trillion, leaving a trade deficit of $550 billion. But Robert E. Scott, senior economist and director of trade and manufacturing policy research at the Economic Policy Institute in Washington, D.C., said the U.S. economy overall is $20 trillion and doesn’t expect the tariffs to “move the dial.”

“Even if tariffs double or triple, it remains a small part of the economy,” Scott said.

The Port of Oakland may fare better than others. Jock O’Connell, international trade adviser at Beacon Economics, said Oakland serves a more regional northern California market than the state’s two largest ports in Los Angeles and Long Beach. With Silicon Valley’s economy surging and a wealthy consumer base, tariffs aren’t likely to cool Bay Area consumers’ spending, O’Connell said, especially since not all of the levies are directly passed on to retail prices.

A pair of economists estimated the average annual household cost of current tariffs at $60, about a tenth of a percent of a typical household’s income, a figure that might reach $270 if all threatened levies were imposed.

O’Connell said the Port of Oakland’s “fortunes are primarily dictated by the economy of northern California, and on the import side, that’s doing very well.”

“There’s every likelihood imports continue to grow,” O’Connell said. “On the export side, things are more mixed.”