President Donald Trump has said that China will buy up to $50 billion in agricultural products, but there are increasing questions about those purchases amidst continuing tensions with China.

No details have been released over what time period China would be expected to spend that amount of money on U.S. farm products. There have been reports that this amount of purchases would be per year, and also reports that this would be a total of $50 billion over several years.

On Friday, Reuters reported that Chinese importers booked fresh purchases of soybeans from Brazil last week, saying that this was unusual because China has usually bought soybeans from the United States between October and January, turning to South America around February.

But Reuters also noted that when prices for soybeans from the United States and Brazil are similar, Chinese importers tend to favor Brazilian beans because of their higher average protein content.

Meanwhile, in a sign of broader U.S.-China tensions, Washington Post columnist Josh Rogin reported Sunday that the Trump administration announced that Chinese diplomats inside the United States are now required to notify the U.S. government before visiting state or local officials as well as academic or research institutions, just as American officials must do in China.