Greece is enforcing its option of an opt-out law that is included in a U.S.-EU deal that allows the US mega grower access to European crops.

Under a law signed in March individual EU countries can seek exclusion from any approval request for genetically modified cultivation across the EU. Specifically, Monsanto sought approval to grow its MON810, a type of pest-resistant corn.

But Greece said no way.

The EU law allows member states to decide themselves, a stipulation that has angered the United States, which wants Europe to open its doors fully to American GM crops as part of a planned EU-U.S. free trade deal.

In a statement this week, the European Commission confirmed that so far only Latvia and Greece had asked for opt-outs from Monsanto’s request to grow their GM crops.

Monsanto fired back at Greece and Latvia, stating that their decision “contradicts and undermines the scientific consensus on the safety” of GM products.

“Nevertheless, we regret that some countries are deviating from a science-based approach to innovation in agriculture and have elected to prohibit the cultivation of a successful GM product on arbitrary political grounds,” the statement said.