According to Greer, the White House's starting point is to stand behind the agreements that have already been made, something that the counterparts, including the EU, are also expected to do.
"We expect our partners to stand behind them (the agreements). None of them have come to me and said the agreement is no longer valid. They want to see how this develops," he says.
The US Supreme Court's decision to invalidate Donald Trump's tariffs came as a shock on Friday.
When Trump responded shortly afterwards by announcing new global tariffs - which he raised from 10 to 15 percent on Saturday - the world reacted with some confusion about which tariff rates actually apply.
