China Extends US Optical Fiber Tariffs After First Anti Circumvention Investigation

US fiber suppliers face duties of up to 78.2 percent

China has extended anti dumping duties to another category of American optical fiber after its first anti circumvention investigation concluded that US exporters had changed trade practices to avoid existing tariffs. The rates range from 33.3 percent to 78.2 percent and apply immediately through April 21, 2028.

The decision, announced by September 5, 2025, covers certain cutoff shifted single mode optical fiber, known in the industry as G.654.C. This specialized fiber carries information over long distances and is used in national communications networks and undersea cables connecting continents.

OFS Fitel faces a duty of 33.3 percent, Corning faces 37.9 percent, and Draka Communications Americas faces 78.2 percent. Other US exporters supplying the products covered by the decision will also face the 78.2 percent rate.

China's Ministry of Commerce said American manufacturers and exporters had changed trade patterns without commercial justification, replacing fiber already subject to duties with a technically similar product outside the earlier order. Investigators concluded that this weakened the existing measures.

The ruling followed an inquiry opened on March 4 at the request of a domestic producer. The investigation lasted about six months and examined whether the substitute product should fall within the scope of China's existing duties on related US optical fiber.

The announcement also came within hours of US Treasury sanctions against Guangzhou Tengyue Chemical and two individuals over alleged involvement in illicit opioid supply chains. Beijing did not link its fiber ruling to those sanctions. Chinese officials presented the decision as enforcement of an existing trade remedy, following a process that had begun months earlier.

What changed in the fiber trade?

China's earlier anti dumping order covered dispersion unshifted single mode optical fiber. The new decision extends that order to certain cutoff shifted single mode fiber after investigators found that US exporters had used the latter product as a substitute.

The Chinese applicant argued that imports under tariff codes already covered by duties had fallen while shipments under similar, uncovered codes had surged. According to the applicant, that shift harmed domestic producers and reduced the protection provided by the original tariffs.

The Ministry of Commerce concluded that the products had similar functions and closely related technical characteristics. Its finding focused on a change in trading practices that allowed shipments to continue outside the earlier order's coverage.

A spokesperson for the ministry's trade remedy bureau described the conduct that investigators considered circumvention:

MOFCOM found that US fiber optic manufacturers and exporters altered trade patterns to ship certain cutoff shifted single mode optical fiber to China without commercial justification. This behavior undermines existing anti dumping measures and constitutes circumvention of China's anti dumping measures on related US optical fiber products.

China's customs authority instructed importers to declare the affected fiber under product code 90011000.01. That instruction gives customs officers and buyers a common classification for the products covered by the expanded duties.

Why this particular fiber matters

Single mode optical fiber carries light signals through a tiny core. It allows information to travel over long distances with very low signal loss, making it a backbone for links between cities, national internet networks, connections between countries and subsea systems.

Multi mode fiber has a larger core and is cheaper over short distances. It is commonly used inside buildings and across campus networks. The products targeted by China's ruling serve a different need: maintaining communications over much longer routes.

Two engineering problems shape the performance of a fiber link. Attenuation describes how quickly a light signal fades as it travels. Dispersion describes how a pulse of light spreads out over distance. Too much spreading blurs the signal and can limit the data rate unless operators use expensive compensation equipment.

Single mode fiber reduces those problems compared with multi mode fiber. G.654.C is engineered for very low attenuation and stable performance at the wavelengths used in transmission over long distances.

Those characteristics make it attractive for undersea routes and remote stretches of land, where installing and maintaining repeaters or amplifiers is expensive. These devices help signals travel farther. Lower signal loss is especially valuable where access to equipment is difficult.

Chinese authorities identified this specialized fiber as the substitute for products already covered by duties. Its role in networks explains why a tariff on a narrow product category can matter to large communications projects.

China is both a major producer and a major consumer of optical fiber. Telecom operators continue to expand national backbones, connections between data centers and international links, while 5G and cloud services send more traffic through fiber networks. Changes in the cost of a specialized grade can affect procurement choices for projects that require very low signal loss.

How the investigation unfolded

The Ministry of Commerce opened the investigation after a Chinese company sought relief. Authorities used questionnaires, hearings and verification at company sites to examine trade patterns and the relationship between the products.

The ministry said the process followed Chinese law and World Trade Organization practices. The outcome expands the product coverage of an earlier order, bringing certain cutoff shifted single mode fiber within the duties applied to related US products.

The main dates connect the new ruling to a much longer history of fiber tariffs:

• 2011: China began imposing anti dumping duties on dispersion unshifted single mode optical fiber from the United States and Europe.
• April 2023: China extended those duties for another five years.
• March 4, 2025: The Ministry of Commerce opened its first anti circumvention investigation following an application from a domestic producer.
• September 2025: Following an inquiry lasting about six months, China announced the expanded duties with immediate effect.
• April 21, 2028: The newly extended measures are scheduled to end.

The connection to the earlier order explains the investigators' central task. They examined whether a switch to a technically similar and interchangeable product allowed exporters to maintain sales while avoiding duties already in force.

What each supplier will pay

The ruling assigns different rates to three named suppliers and sets the highest rate for other US exporters of the covered products:

• OFS Fitel: 33.3 percent.
• Corning: 37.9 percent.
• Draka Communications Americas: 78.2 percent.
• All other US exporters covered by the decision: 78.2 percent.

Draka Communications Americas and exporters subject to the general rate face a duty 44.9 percentage points higher than OFS Fitel, calculated from the published rates of 78.2 percent and 33.3 percent. Corning's rate falls between those levels.

Importers of covered products typically must pay duties or cash deposits at customs equal to the specified percentage of the declared value. Earlier Chinese fiber cases have also produced rates at levels similar to those in the new decision.

Corning is a major producer of fiber and cable. OFS Fitel is a US manufacturer of fiber and cable, while Draka Communications Americas belongs to a global group with facilities across several regions. The effect on each company will depend on its exposure to China's market and its production footprint outside the United States.

Exporters not named individually face the 78.2 percent rate unless they obtain different treatment through later administrative procedures. The decision therefore affects both the named suppliers and other American companies selling the specified fiber into China.

What anti dumping and circumvention mean

Anti dumping investigations examine allegations that foreign exporters sell goods at unfairly low prices and injure domestic producers. When a government confirms dumping and injury, it can impose extra import duties, with individual rates for named companies and a general rate for others.

Authorities commonly examine production costs and compare export prices with a normal value. When a suitable price comparison is unavailable, that normal value may be constructed through a detailed calculation. These assessments help determine the duty imposed.

An anti circumvention investigation addresses what happens after a trade remedy is in place. It examines whether changes in products, trade patterns or routing through other countries are being used to avoid an existing order.

Authorities that confirm circumvention can expand an order to cover the substitute product or tighten customs classification rules. Some jurisdictions also allow duties to be applied to earlier shipments. China's fiber decision extends product coverage and specifies a customs code.

Many WTO members use anti circumvention measures to maintain the effect of trade remedies. China's first case of this kind signals closer enforcement of the boundaries of its earlier anti dumping findings.

Shi Xiaoli, director of the WTO Law Research Center at China University of Political Science and Law, described the legal purpose of such investigations:

The investigation aligns with Chinese laws and WTO practices. If circumvention is confirmed, authorities can expand the scope of taxation to close loopholes and ensure that earlier measures remain effective.

Bao Jianyun of Renmin University also linked the decision to established international practice. Bao said China's first use of the tool would make enforcement more effective, strengthen protection for domestic industry and signal Beijing's determination to maintain a fair competitive environment for Chinese companies.

Why the sanctions timing drew attention

The US Treasury action against Guangzhou Tengyue Chemical and two individuals concerned their alleged roles in illicit opioid supply chains. China's fiber announcement followed within hours, placing two economic enforcement actions close together during a tense period in relations.

Beijing described the fiber ruling as a legal step to preserve the effectiveness of duties already in place. The investigation's March 4 opening places the start of that process months before the sanctions announcement.

The parallel actions came amid disputes over advanced manufacturing and technology supply chains. Semiconductors, electric vehicles, batteries and telecommunications have all become areas of friction between Washington and Beijing.

Washington has tightened export controls on advanced chips and related equipment while maintaining or increasing tariffs on a wide range of Chinese goods. Beijing has used trade remedy investigations alongside export licensing requirements and cybersecurity reviews.

Both governments commonly cite domestic law and WTO rules when explaining their measures. For businesses, sanctions, export controls and import duties now overlap across the economic relationship, adding several different sets of rules to decisions about where to buy, manufacture and sell.

How Chinese buyers may respond

Chinese carriers, cloud platforms and undersea cable groups face an immediate sourcing decision for the covered fiber. The duties are likely to encourage purchases from domestic producers or suppliers outside the United States.

China's leading fiber manufacturers, including YOFC and FiberHome affiliates, have substantial capacity and a strong presence in national projects. Domestic manufacturers can produce similar grades at scale, reducing the risk of delays when buyers change suppliers.

Procurement teams may still face higher prices in the short term. Replacing a supplier can require fresh negotiations, and fewer competing suppliers for a particular grade can affect the terms buyers receive.

The change may also alter bidding for networks spanning long distances and for international cable routes connected to Chinese landing stations. Buyers will have to consider the required fiber specification alongside the import duty and the availability of alternative suppliers.

For projects that need very low signal loss, choosing a cheaper but less suitable fiber may carry other costs. Operators are likely to prioritize continuity and compliance with technical requirements where the specified grade is necessary for performance.

How US suppliers and project owners are affected

US suppliers now face narrower access to a major market for this particular product. They may focus on projects outside China or supply customers from production facilities overseas, where those facilities meet the country of origin rules relevant to the order.

Telecom projects running over several years often use supplier agreements covering multiple regions. That can provide room to redirect some orders, although any change depends on the order's precise product scope and customs enforcement at ports.

The effect on individual contracts, project prices and supplier decisions has not been quantified. Company exposure to China and the location of manufacturing facilities will help determine how much business is affected.

Project owners also have to consider the full cost of building and operating a network. Fiber is only one part of spending that includes cable manufacturing, installation, rights of way, amplifiers, repeaters and other network equipment.

A higher fiber price can influence a purchasing decision, while the cost of redesigning a route or changing equipment may influence it in another direction. For networks crossing oceans or remote areas, maintaining the required performance remains central to procurement.

The immediate change is therefore specific: certain US optical fiber that previously sat outside an existing duty order now falls within it. Chinese buyers must account for the new charges, while suppliers must assess their market exposure and production arrangements before the measures' scheduled end on April 21, 2028.

Key Points

• China's first anti circumvention investigation extended existing optical fiber duties to certain US cutoff shifted single mode fiber, known as G.654.C.
• The duties take effect immediately and run through April 21, 2028.
• OFS Fitel faces 33.3 percent, Corning 37.9 percent, and Draka Communications Americas and other covered US exporters 78.2 percent.
• The Ministry of Commerce concluded that exporters changed trade patterns without commercial justification to avoid existing duties.
• The investigation opened on March 4, 2025, and included questionnaires, hearings and verification at company sites.
• Customs instructed importers to declare the affected fiber under product code 90011000.01.
• The ruling expands an order on related US fiber imposed in 2011 and extended in April 2023.
• The announcement followed US sanctions against Guangzhou Tengyue Chemical and two individuals; Beijing did not link the actions.
• Chinese network builders may shift purchases toward domestic producers and suppliers outside the United States.