There is no written agreement yet on a trade deal between South Korea and the United States announced by President Donald Trump this week, the Asian nation's trade minister said on Friday.

The U.S. tariff on South Korean imports will be 15%, Trump said after meeting its ministers on Wednesday, down from a threatened 25%, but the U.S. gave scarce details, apart from social media posts by him and Commerce Secretary Howard Lutnick.

Speaking to reporters as he arrived home from a visit to Washington, Trade Minister Yeo Han-koo said the two sides had an oral negotiation because of time constraints.

"What we felt during this negotiation is that the U.S. trade environment is fundamentally changing. This is completely different from the first Trump term," Yeo said of the deal easing tension with a top-10 trading partner and key Asian ally.

"I think we are entering a new normal era. So, although we have overcome this crisis, we cannot be relieved, because we do not know when we will face pressure from tariffs or non-tariff measures again."

The White House, which issued factsheets on trade deals with Japan and the European Union a day after striking them, has not yet released a separate one on the pact with South Korea.

Trump said South Korea would invest $350 billion in the United States in projects "owned and controlled by the United States" and selected by him.

Lutnick said 90% of profits from the investments would go to the American people, while White House Press Secretary Karoline Leavitt said they would go to the U.S. government to help repay debt.

More discussions were necessary on the investment fund's profit structure, said Industry Minister Kim Jung-kwan, who returned with Yeo.

Finance Minister Koo Yun-cheol, also one of the negotiation team, said detailed plans for the $350-billion investment would need be established.

Wednesday's deal did not tackle most non-tariff barriers discussed during working-level talks, as well as security and foreign exchange aspects.