Sanctions are Donald Trump's weapon of choice

Economic measures are a useful middle ground between weapons and words, but they do not work in isolation

US President Donald Trump speaks in front of a poster that reads "Sanctions Are Coming" during a meeting in White House. Al Drago / Bloomberg

"We will devastate Turkey economically if they hit Kurds," wrote US President Donald Trump on Twitter on Sunday. It came after his shock decision in December to withdraw 2,000 American troops from Syria, and Turkish President Recep Tayyip Erdogan's threat to "crush" US-backed Kurdish forces in the country. Mr Trump's declared commitment to protect a group that has bravely defended civilians from ISIS is welcome. But at a deeper level, it speaks to the type of president he has become. While some of his predecessors have favoured diplomacy or military force, economic sanctions have become Mr Trump's foreign policy weapon of choice. And while they are a useful middle ground between weapons and words, economic measures are not always as effective as Mr Trump might suggest.

In 2017 alone, the US Treasury sanctioned a record 944 foreign individuals, organisations and companies. In a single month last year, they hit Colombia, Pakistan, Lebanon, Libya, Somalia and the Philippines. And on Sunday, as Mr Trump threatened Ankara with economic devastation, his ambassador to Germany, Richard Grenell, warned that European companies could face financial penalties for their investment in the Russian Nord Stream 2 gas pipeline. Similar threats were issued to EU companies operating in Iran. Today, no one is safe from the possibility of US sanctions, sparking consternation in European capitals.

When it comes to regimes that wilfully flout diplomatic norms, such as Iran and North Korea, sanctions are the only way to bring their leaders to bear. But they do not work in isolation and must instead be enforced multilaterally. In a statement of political and economic intent, China and Russia have vowed to continue purchasing Iranian oil, taking the teeth out of Mr Trump's measures. Meanwhile, other players in global trade, like Gulf states and European companies, can suffer economically from sanctions on Iranian exports. Ultimately, Mr Trump's unilateral sanctions and harsh tariffs – like those imposed on Chinese imports last year – serve to harden anti-US feeling. A penalised Beijing is less likely to assist the US in its dealings with Iran and North Korea. Equally, a sour Mr Erdogan is more likely to ignore American concerns over Syria.

It is worth noting that sanctions often hit vulnerable citizens and leave their dictatorial leaders unscathed, as the crippling sanctions imposed on Iraq after Saddam Hussein’s invasion of Kuwait in 1990 attest.

Mr Trump's fondness for economic penalties reflect the former real estate developer in him and his overwhelmingly transactional view of the world. But while steps from his administration to protect the Kurds in northern Syria, rein in the worst excesses of Tehran's destabilising regime and bring North Korea to the table are welcome, Mr Trump would be wise to take a more considered approach to his frequent and hasty deployment of economic sanctions.