A new report has found that price hikes in May and April went beyond what the announced tariffs could reasonably explain.

As U.S. President Donald Trump and China's leader Xi Jinping prepare to kick off talks on Thursday, U.S. negotiators have signaled they seek a return to a fragile trade war truce, but tensions remain high and longer-term economic irritants will likely persist between the geopolitical rivals.

China has signed an expanded free trade agreement with the Association of Southeast Asian Nations. Premier Li Qiang has promoted economic ties with Beijing as an alternative to U.S. protectionist policies.

A tariff hike could potentially damage the Chinese economy. The U.S. imported about $438 billion worth of goods and services from China last year, making it the largest destination for China’s exports. In all, that figure accounts for about 15% of China’s exports, according to the Office of the U.S. Trade Representative.

Major indexes all closed at all-time highs, with the S&P 500 ending above 6,800 for the first time ever.

Soybean prices reached a 15-month high Tuesday as the commodity, which makes up the U.S.’ largest agricultural export, is embroiled in the trade war between the U.S. and China that’s affecting American farmers. Soybean prices have risen more than 11% since July last year as the crop has become a major tool in U.S.-China trade negotiations.

Iowa Republicans are urging the Trump administration to move to restore access to foreign soybean markets amid a trade standoff with China.

Global stocks rallied on Monday to a fresh intraday record while the dollar eased on optimism that a potential trade deal was on the horizon between China and the U., as investors awaited a slew of central bank policy announcements and earnings from several megacap companies.