US President-elect Donald Trump says Jamieson Greer will be his trade representative after he takes office on 20 January 2025.

The announcement came after Trump threatened new tariffs – which are taxes on imported items – on China, Canada and Mexico to get them to clamp down on the illegal flow of people and drugs to the US.

Greer, a trade lawyer, is a veteran of Trump’s first presidency – during which he played a key role in imposing tariffs on goods from China.

This time, Greer would be involved in “reining in the country’s massive trade deficit, defending American manufacturing, agriculture, and services, and opening up export markets everywhere,” Trump said in a statement.

It is Trump’s longstanding policy to encourage consumers to buy American products by making imported goods more expensive. A number of appointees to his top team for 2025 take a particularly hawkish view of China.

Greer, who is also a veteran of the US Air Force, served during Trump’s first term as chief of staff to US trade representative Robert Lighthizer.

During that period, the US and China – the world’s two largest economies – became locked in a bitter trade battle, imposing tariffs on hundreds of billions of dollars worth of one another’s goods.

Tariffs imposed on China during his first stint in the White House were an effort to “spur the return of manufacturing jobs to America, and reverse decades of disastrous trade policies,” Trump said in his statement unveiling Greer.

Greer was also part of the team that negotiated a new trade deal with Canada and Mexico to replace the previous North American Free Trade Agreement (Nafta).

His appointment is one of those that require confirmation by a vote of US senators.

Another of Trump’s picks on Tuesday will be a direct appointment. Kevin Hassett has been named Trump’s top economic adviser, who will head up the White House National Economic Council.

A tariff is a domestic tax levied on goods as they enter the country, proportional to the value of the import.

The charge is physically paid by the domestic company that imports the goods, not the foreign company that exports them. In that sense, it is a straightforward tax paid by domestic US firms to the US government.

Earlier this week, Trump vowed to impose new tariffs on goods from China, Canada and Mexico – America’s top three trade partners.

He said he would introduce 25% tariffs on imports from Mexico and Canada and “an additional 10% tariff, above any additional tariffs” on imports from China.

The three countries responded by saying the pledge could upend their economies, as well as that of the US.

Although analysts have suggested that Trump’s tariff threats could prove to be a negotiating tactic, some businesses told the BBC that they were already having economic consequences as they started to stockpile goods and shift supply chains.

With Greer and other names added, Trump’s top team is now largely in place.

On Tuesday, he also unveiled leading Covid lockdown sceptic Jay Bhattacharya to be the next director of the National Institutes of Health (NIH).