U.S. wheat futures rose 6 percent to a two-week high, while corn rose 1.6 percent on Monday as Russia’s withdrawal from the Black Sea export agreement added to worries about global supplies, Reuters reported.

Soybeans followed this trend, with the most active SF3 contract in January setting a record for the previous month.

Wheat contracts for December delivery on the Chicago Mercantile Exchange were up 53 cents at $8.82 a bushel after hitting $9.93 a bushel, the highest level since Oct. 14. March wheat contracts hit a high of $13.63 a bushel.

“Cereals and oilseeds markets rose sharply overnight, led by wheat, as fears of food shortages rose again after Russia pulled out of the Black Sea Trade Agreement,” StoneX Chief Commodity Economist Arlan Suderman said in a note to clients.

Moscow on Saturday suspended its participation in the Black Sea agreement in response to what it called a major attack by Ukrainian drones on its navy in Russia-annexed Crimea.

Grain ships left Ukrainian ports on Monday, a sign that Moscow has not renewed its blockade of the Black Sea.

But delivery could be disrupted again, especially if insurers no longer cover it. Lloyd’s of London Ascot has suspended coverage for new shipments through Ukraine’s Black Sea grain corridor until it clears up the situation in the area, a senior official said.

Russian stocks were overshadowed by market pressure from a stronger dollar, which tends to make U.S. grain less competitive globally.