How Do Tariffs, Quarantine Rules and Import Bans Become Diplomatic Weapons?

How does economic coercion differ from an ordinary trade restriction?

The tools are usually ordinary; what matters is what they are used for. Tariffs, sanitary checks, customs clearance and visas are routine government business. They become economic coercion when they are used to make another country change a political decision. The EU’s Anti-Coercion Instrument, adopted in 2023, covers a third country applying or threatening a measure affecting trade or investment in order to stop the EU or a member state from taking a particular act, or to make it drop, change or adopt one, “thereby interfering in the legitimate sovereign choices” of the Union or its members.

By that test, some tough-looking measures belong elsewhere. Thailand has taxed low-value imports since 2024 and in 2026 stepped up its checks on nominee shareholders. Chinese-backed firms draw particular attention, but the rules apply to every foreign investor and ask for compliance with Thai market rules, not a change in Beijing’s policy. The EU’s freeze on Hungary’s funds is a different case: it is pressure, but its conditions are written into EU law. Payments can be suspended when rule-of-law failings affect the Union’s financial interests, freezes and releases follow set procedures, and the European Parliament has taken the Commission to court over one release.

Nor is coercion always covert. In 2025 Washington openly tied its extra tariffs on China to Beijing’s counternarcotics cooperation, raising the rate from 10% to 20% before cutting it back to 10% in November (the explainer on counternarcotics cooperation tells the story). Formal sanctions, likewise, state their legal basis and their targets. More common is the other end of the range: the measure looks routine, and the government behind it does not acknowledge any political link. That end is the subject here.

Why are quarantine and customs checks the tools used most often?

Because they are the easiest to deny. Food imports pass through several gates: certificates must be accepted, exporters registered, consignments sampled and cleared. A regulator need not change a single standard. Suspending recognition of one certificate, delisting a few exporters or quietly raising the inspection rate is enough to keep a whole shipment out. The WTO’s Agreement on Sanitary and Phytosanitary Measures requires measures to rest on risk assessment, but it also allows provisional ones where the scientific evidence is insufficient, which leaves considerable room in enforcement (see the analysis of how conflict rewrites food safety and quarantine).

Farm produce is also the least able to wait. Comparing four cases in 2024, the OECD found that agri-food products and raw materials such as timber were the most frequent targets and the hardest hit. Perishables lose value with each extra day at the border and are hard to sell elsewhere, while a measure justified on sanitary grounds takes time to disprove and can be lifted whenever the imposing government chooses.

Examples are easy to find. In April 2014, after annexing Crimea, Russia suspended imports from six Ukrainian dairy producers for breaching hygiene rules; from 28 July it banned Ukrainian dairy altogether, now citing antibiotic residues and bacterial contamination. A Taiwanese Representative Office opened in Lithuania in November 2021; from December, according to the European Commission and the OECD, Lithuanian goods were turned away by Chinese customs, some stuck in IT systems and others simply not processed, with no official explanation. In January 2022 Lithuania’s exports to China were 0.17% of their 2019 monthly average.

Tariffs are much harder to deny. They have to be published and need a legal basis, which also exposes them to the courts. On 20 February 2026 the US Supreme Court ruled that the International Emergency Economic Powers Act did not authorise the president to impose tariffs, and the fentanyl-justified duties stopped being collected on 24 February.

If retaliation is never admitted, how can you tell?

No single piece of evidence settles it; what counts is a pattern. Borrowing the anti-corruption practice of looking for “red flags”, the OECD lists recurring features: a sudden, large fall in trade confined to a few products while the same goods from other suppliers keep flowing; several measures arriving within a short period, coinciding with a political decision the imposing country objects to; and officials linking the measures, in other settings, to that decision.

The cases show further tells. The stated reasons shift: Russia’s ban on Ukrainian dairy moved from hygiene rules to antibiotic residues, and when it was widened to all products under plant-health control the grounds became labelling, pests and transshipment. Standards stay put while lists change: Russia never set stricter residue limits for Ukraine, working through certificates and approved-supplier lists instead. Treatment is uneven: when China suspended aquatic imports from 178 Taiwanese firms in December 2022 for incomplete registration, Taiwan’s Council of Agriculture said Taiwan had been given a stricter deadline for its paperwork than other countries.

Errors run in both directions. Pests and drug residues are real, and coincidence in timing is not causation; calling every rejected consignment retaliation lets genuine quality problems slide. Equally, finding no evidence does not mean there was no pressure. The OECD notes that when a threat works and the target gives way in advance, no measure is ever imposed, and that other countries watching may steer clear of decisions likely to provoke one. Neither appears in any statistic. Using border enforcement as a bargaining chip raises the same problem of proof, as the explainer on outsourced borders describes.

What has Taiwan faced?

Farm and fishery products come up most often. At the end of February 2021 China announced it would stop importing Taiwanese pineapples from 1 March, citing scale insects; Beijing said 28 shipments had failed inspection in 2020, while Taiwan’s Council of Agriculture said it had been notified of only 13. By the council’s figures, about nine-tenths of Taiwan’s fresh and chilled pineapple exports went to China in 2020. Sugar apples and wax apples followed in September 2021 and grouper in June 2022; China had taken 91% of Taiwan’s grouper exports by volume in 2021.

The timing was most striking in August 2022. Before US House Speaker Nancy Pelosi landed in Taipei late on 2 August, China’s customs administration had already suspended imports of many Taiwanese food products. On 3 August it halted Taiwanese citrus, chilled hairtail and frozen horse mackerel, citing pests, excess pesticide residues and packaging that tested positive for Covid-19, and China’s commerce ministry suspended exports of natural sand to Taiwan the same day.

From 2023, tariff preferences joined the toolkit. At the end of 2023 China announced that it was suspending concessions on 12 products under the Economic Cooperation Framework Agreement (ECFA), and on 31 May 2024 it announced that concessions on another 134 would end on 15 June. Formally this was a tariff adjustment under ECFA, but the same day the spokesman for Beijing’s Taiwan Affairs Office said the root cause was the Lai Ching-te administration’s stubborn insistence on a pro-independence stance and its refusal to recognise the 1992 Consensus.

Tourism belongs to the same kit. On 31 July 2019 China’s Ministry of Culture and Tourism announced that, in view of the current state of cross-strait relations, it would stop issuing individual travel permits to Taiwan for residents of 47 cities from 1 August. This time no technical reason was given at all; the notice named the relationship itself.

What does this mean for Taiwan?

First, the products singled out tend to be those most dependent on the Chinese market. Pineapples and grouper both sent around nine-tenths of their exports to China, which fits the OECD’s observation that coercers often pick goods for which they are the main buyer and the target has no quick alternative, at little cost to themselves. The more concentrated the market, the bigger the lever in the other side’s hands, and reducing that concentration is the job of de-risking (the explainer on de-risking and decoupling goes further).

Second, diversification works, but not for every product. Council of Agriculture figures show China’s share of Taiwan’s fresh fruit exports falling from 84.4% in 2016 to 41.4% in 2021; in 2022, up to 4 August, Taiwan exported 21,328 tonnes of pineapples, 18,403 of them to Japan. The OECD cases show how much depends on the product: Moldova’s wine, spirits and canned produce shifted to the EU, its fresh fruit far less; Australian coal found new buyers, while live rock lobster and bottled wine lost the premium they had commanded in China.

Third, the pressure also lands on countries that deal with Taiwan. After a Taiwanese Representative Office opened in Lithuania, Lithuanian exports to China all but disappeared. When Papua New Guinea ordered the closure of Taiwan’s office in Port Moresby in July 2026, Prime Minister James Marape denied any economic coercion by China, yet the same statements kept pointing to China’s capacity to absorb PNG’s LNG, farm, fisheries and timber exports. That does not prove Beijing traded market access for a diplomatic decision, but it shows how hard the two are to pull apart (see the analysis of PNG’s multi-market hedging).

Taiwan has pulled the same lever itself. After PNG announced the closure, the state-owned CPC suspended spot purchases of PNG’s LNG while honouring its long-term contract, and the foreign ministry said it would decide whether to resume buying or retaliate further once PNG responded formally. With the long-term contract intact, the effect is limited to redirecting some short-term cargoes.

What can a country under pressure do?

The traditional route is the WTO, but proceedings are slow, and the measure first has to be shown to exist. The OECD notes that proving a sanitary measure breaches WTO rules may be difficult and time-consuming, especially when it is opaque or the imposing government will not engage in good faith. On 27 January 2022 the EU took China to the WTO over its trade measures against Lithuania. The Commission’s evidence included refusals to clear Lithuanian goods through customs, rejected import applications from Lithuania, and pressure on companies in other member states to remove Lithuanian inputs from supply chains serving China.

The Commission said at the same time that, to deal with such cases in future, it had proposed an Anti-Coercion Instrument the month before. The regulation took effect on 27 December 2023 and works in stages. The Commission examines a case, normally within four months; the Council decides by qualified majority whether coercion exists, normally within eight to ten weeks; the Commission then seeks a settlement through negotiation, international adjudication or mediation, and adopts countermeasures only if that fails. These can include tariffs, import and export restrictions, and limits in public procurement, services, foreign direct investment, intellectual property and financial services, as well as restrictions, under the EU’s own sanitary and phytosanitary rules, on placing the other country’s goods on the market. They must be proportionate and may not exceed the injury to the EU.

Deterrence comes first. The regulation sets its aim as deterring economic coercion or obtaining its cessation, with countermeasures as a last resort. The G7’s Coordination Platform on Economic Coercion, launched in Hiroshima in May 2023, follows the same logic: early warning and rapid information sharing, so that a coercer expects to face more than one country. Coercion is also one reason governments now manage economic dependence as a matter of economic security.

In the long run, the basic defence is lower dependence. The OECD finds that new free trade agreements appear to have helped Moldova diversify: Russia’s share of the value of its goods exports fell from 28% in 2011 to 9% in 2021, while trade with the EU and other new partners grew. Taiwan sits outside the EU instrument; what it can do is diversify its markets, document the measures it meets and make sure partners see them. The OECD observes that collective attention has made it easier for targeted economies to draw notice to coercion and has helped deter further cases.