China is a crucial part of the business of major ports in Washington state, a transportation executive told a House of Representatives panel at a hearing on the impact of tariffs.

"Our success as an airport and seaport gateway is inextricably linked to China. Last year, more than $27 billion in imports from China came through Seattle and Tacoma cargo terminals, with an additional $1.1 billion in imports from China via Sea-Tac," John Wolfe, chief executive officer of the Northwest Seaport Alliance, told the House Ways and Means Committee in Washington last Thursday.

The Northwest Seaport Alliance is a marine cargo operating partnership of the ports of Tacoma and Seattle and the fourth-largest container port complex in the United States.

Sea-Tac is the Seattle-Tacoma International Airport.

"In addition, almost $5 billion in exports to China traveled through our cargo terminals in 2017, plus another $2.2 billion in exports to China through Sea-Tac," Wolfe said.

He said that "while it is impossible to truly estimate the impact of these tariffs, roughly $8 billion in two-way trade through our airport and seaport will potentially face some level of increased tariff".

The American Association of Port Authorities estimates that for every $1 billion in exports shipped through US seaports, 15,000 jobs are created, and the converse is likely true as well, which means that this $8 billion in trade likely represents 120,000 jobs, he said.

"The risk is significant because thousands of our jobs are tied to trade," Wolfe told China Daily on Monday. "Our marine cargo operations in our Seattle and Tacoma harbors support more than 48,000 jobs, while Sea-Tac's air cargo operations help create over 5,200 jobs."

Also, more than 60 percent of goods imported through the NWSA are sent beyond the Northwest region.

"Our greatest concern is that we are going to potentially affect jobs associated with trade in the state of Washington, and it is not only in our state. We would also risk impact … through the whole supply chain in the Upper Midwest," Wolfe said.