Praise Trump and speak simply.

South Korean ministers tasked with reaching a trade deal with United States President Donald Trump said they prepared for the talks by role-playing and gathering advice on how to communicate with an unpredictable leader.

Among the advice they received was to call Trump a "great man" and to speak as simply as possible, Industry Minister Kim Jung-gwan told reporters in Washington after the deal was announced on Wednesday.

The stakes were particularly high for South Korea, an export-driven economy, and Kim and the other members of the delegation have only been in office for a few weeks, after President Lee Jae-myong won a snap election in June.

Kim called Trump a "master negotiator" and said that all members of the team, which included Finance Minister Koo Yun-chol and Trade Minister Jeon Han-ku, had been taking turns in the role of the US president to prepare.

“We tried to speak like President Trump, and his way of speaking is very concise and direct,” Kim said. “We prepared a lot of scenarios on our own so we knew how to answer different questions.”

Ku, as reported by Reuters, said they only found out for sure that they would meet with Trump when they saw it on social media.

The meeting itself lasted about half an hour, and the two sides outsmarted each other over the size of the investment fund, which was ultimately agreed upon at $350 billion, Ku said.

"We prepared a lot of negotiation strategies in advance that our colleagues used and thought a lot about how to respond, so the negotiations went very smoothly," he said.

Jeo quoted Trump as saying that he personally very rarely engages in discussions with officials who are not heads of state, and that this means he "has great respect for South Korea and attaches great importance to it."

After the talks, Trump said the US would impose a 15% tariff on imports from South Korea, down from a previously announced 25%, as part of a deal to ease tensions with one of the ten largest trading partners and a key ally in Asia.

South Korea appears to have avoided the worst-case scenario, Chung In-kyo, a former South Korean trade minister, told Reuters. But he added that opinions on the deal could change if the $350 billion in investment is not spent wisely.

It is not clear exactly what the sum entails, where the funding will come from, within what timeframe the agreements will be implemented, or to what extent their terms will be binding, the British agency points out.

South Korea is one of three countries in the Asia-Pacific region that has a comprehensive free trade agreement with the United States, but that has not spared it from new tariffs. Seoul has come under fierce criticism from Trump over its trade surplus and the cost of maintaining the roughly 28.500 US troops stationed there to defend against North Korea.

The talks were an early test for South Korean President Lee Jae-myung, who took office in June after snap elections. He said the deal removed uncertainty and set U.S. tariffs at or below the level of major competitors.

“We have crossed a major hurdle,” Lee said in a Facebook post. Trump announced that Lee would visit the White House “in the next two weeks.”

South Korean companies welcomed the agreement, saying it would reduce uncertainty.