WASHINGTON • The US administration has announced it would provide up to US$12 billion (S$16.3 billion) in emergency relief for farmers hurt by President Donald Trump's trade war, moving to blunt the financial damage to US agriculture and the political fallout for Republicans in the wake of Mr Trump's protectionist policies.

Unveiled two days before Mr Trump is scheduled to visit Iowa, a politically important state that is the nation's top soya bean producer, the farm aid appeared calculated to show that Mr Trump cares about farmers and is working to protect them from the worst consequences of his trade war.

But the relief money, announced on Tuesday by the Department of Agriculture, was also an indication that Mr Trump - ignoring the concerns of farmers, their representatives in Congress and even some of his own aides - plans to extend his tit-for-tat tariff wars.

"The actions today are a firm statement that other nations cannot bully our agricultural producers to force the United States to cave in," Secretary of Agriculture Sonny Perdue said during a call with reporters to unveil the aid scheme. The move drew swift condemnation from many farm groups and lawmakers, including several in Mr Trump's own party, who worry about a cascade of unintended consequences that may be just beginning.

One farm-group study estimates that US corn, wheat and soya bean farmers have already lost more - US$13 billion - than the proposed aid. The prospect of retaliation has upended global markets for US farm exports, and farmers are warning that tariffs are costing them valuable foreign contracts that took years to win.

"The US Department of Agriculture is trying to put a band-aid on a self-inflicted wound," Republican Senator Patrick Toomey wrote on Twitter. "This bailout compounds bad policy with more bad policy."