US Agriculture Secretary Tom Vilsack warned Mexico's president that the US would be forced to take legal action if no "acceptable resolution" was found.A ban would have "significant impact" on US-Mexico trade, Mr Vilsack had earlier warned.The decree caused huge concern among US corn exporters and with the deadline approaching, efforts by the US to sway President López Obrador to drop or soften the planned ban have increased."We must find a way forward soon," Mr Vilsack said, warning that the US "would be forced to consider all options, including taking formal steps to enforce our legal rights under the USMCA", referring to free trade agreement between the US, Mexico and Canada.Mexico prides itself on being the place where thousands of years ago humans began to domesticate corn for the first time and the country boasts dozens of heirloom varieties."