A senior German politician said on Sunday the European Union and Washington could negotiate further and postpone higher import duties after U.S. President Donald Trump ramped up the trade war by threatening a hike in tariffs on the bloc.

President Donald Trump posted letters to the leaders of Mexico and the European Union, saying they had not done enough to head off the new tariffs.

The European Commission responded to Trump's announcement in a written statement, saying it remains ready to reach an agreement, while also taking "necessary steps to safeguard EU interests, including the adoption of proportionate countermeasures.

The European Union braced on Friday for a possible letter from U.S. President Donald Trump outlining planned duties on the United States' largest trade and investment partner after a broadening of his tariff war in recent days.

European producers say streamers investment obligation will improve local content, increase competitiveness against 'stone cold' U.S. market.