BRUSSELS, March 1 (Reuters) - The European Union said on Thursday it would react firmly with a proposal within days for WTO-compatible countermeasures against the United States for trade restrictions on steel and aluminum, which it called a “blatant intervention” to protect U.S. industry.

“We strongly regret this step, which appears to represent a blatant intervention to protect U.S. domestic industry and not to be based on any national security justification,” the European Commission chief executive Jean-Claude Juncker said in a statement.

“We will not sit idly while our industry is hit with unfair measures that put thousands of European jobs at risk ... The EU will react firmly and commensurately to defend our interests.” (Reporting by Alissa de Carbonnel @AdeCar Editing by Peter Graff)