(Reuters) - U.S. and Chinese negotiators meet in Washington on Thursday and Friday to try, once again, to defuse a trade war that has roiled markets and triggered tit-for-tat tariffs on hundreds of billions of goods traded between the world’s largest economies.

The meetings come days after the U.S. Department of Commerce blacklisted 28 Chinese companies, and China and the U.S. started reciprocal visa bans. Chinese officials say they have little expectation of significant progress.

If negotiators cannot come to an agreement, a new set of punitive U.S. tariffs kicks in on Oct. 15 on about $250 billion of Chinese goods, and then both countries put tariffs on billions of dollars more of each others’ goods on Dec. 15.

Here is what is set to take effect in the next few weeks:

U.S. OCT. 15 INCREASE

A proposed Oct. 15 tariff rate boosts to 30% a duty of 25% already in place on at least $250 billion worth of Chinese imports.

Set to take effect on Oct. 1, the higher tariff was delayed late in September by Trump “as a gesture of good will.” The 25% tariffs were adopted over nearly a year, from an initial tranche of largely non-consumer goods in July and August 2018, including machinery and electronic components such as semiconductors and printed circuit boards and many chemicals.

Later the U.S. added consumer goods and building products, including furniture, vacuum cleaners, lighting fixtures, handbags and vinyl flooring.

FILE PHOTO: Chinese and U.S. flags flutter near The Bund, before U.S. trade delegation meet their Chinese counterparts for talks in Shanghai, China July 30, 2019. REUTERS/Aly Song/File Photo/File Photo

U.S. DEC. 15 TARIFF INCREASE

Two months later, the U.S. plans to target an additional tariff of 15% at about $300 billion in imports from China.

These had already been hit with a tariff of 15% on Sept. 1, in a list mostly of consumer products, based on a Reuters analysis of 2018 U.S. Census Bureau data. It includes flat panel television sets, flash memory devices, power tools, cotton sweaters, bed linens, multifunction printers and some footwear.

The largest category of targeted products covers smart watches, smart speakers, Bluetooth headphones and other internet-connected devices spared in a prior round of tariffs, with Chinese imports estimated at $17.9 billion annually by the Consumer Technology Association.

An additional round of 15% U.S. tariffs is also scheduled for Dec. 15. It targets Chinese goods not previously covered by U.S. duties and will hit the consumer technology sector hard, including cellphones, laptop and tablet computers, categories that formed a combined $80 billion of imports last year.

About $12 billion worth of Chinese toy imports would also suffer. Trump has said he delayed tariffs on such products to avoid hurting Christmas season sales of Apple Inc and others.

The Dec. 15 list covers about $156 billion worth of total 2018 imports from China, based on U.S. Census Bureau data, and includes a wide range of other consumer goods, from plastic tableware and light-emitting diode lamps to clothing.

If fully adopted, U.S. tariffs proposed and already levied will cover virtually all imports from China, worth about $550 billion, by Dec. 15.

BEIJING’S DEC. 15 RETALIATION

After Trump early in August announced plans to tax virtually all remaining Chinese imports, Beijing said it would impose additional 5% or 10% tariffs on a total of 5,078 product categories from the United States, representing about $75 billion annually.

The first stage of these tariffs took effect on Sept. 1, with a second tranche to follow on Dec. 15. This list targeted U.S. crude oil for the first time with a 5% tariff, while the tariff on U.S. soybeans jumped to 30% from 25%. U.S. beef and pork tariffs also increased by 10%.

In September, Beijing announced it would exclude some farm products, including soybeans and pork, from the additional levies.

China already had tariffs ranging from 5% to 25% on about $110 billion worth of U.S. products, including soybeans, beef, pork seafood, vegetables, liquefied natural gas, whiskey and ethanol.

If the Dec. 15 tariffs are enforced, China will only have about $10 billion worth of $120 billion in annual U.S. imports untouched by tariffs, with the largest category consisting of large commercial aircraft built by Boeing Co.

U.S. TARIFF EXCLUSIONS

The Trump administration has previously excluded some Chinese-made household furniture, including cribs and other baby safety products, and bibles and other religious texts, from the Sept. 1 and Dec. 15 tariff rounds.

Some, including internet modems and routers, were removed because they had already been hit with 25% tariffs, while others were dropped for safety or religious reasons. Chinese-made rosaries and religious medals, however, still face 15% tariffs on Sept. 1.