U.S. president Donald Trump | Win McNamee/Getty Images Brussels publishes US tariffs retaliation lists totaling €6.4 billion The list includes products worth €2.8 billion, which the EU can target with tariffs of 25 percent at any moment after notifying the list to the WTO.

Brussels Friday published two lists with American products that it will target if U.S. President Donald Trump imposes increased tariffs on EU exports of steel and aluminum.

A senior European official said the EU's response list was for "stakeholder consultations" and added that the total value of American exports targeted could reach "€6.4 billion all added together."

The Commission needed to act now to make sure it notified the lists to the WTO within a 90-day deadline, but the decision whether to use the lists would be taken only after three months.

Brussels needed to act now because "you may be exempted today and three months later the situation changes," the official said. "At this point of time we need to be sure that we can preserve our rights ... [however], the decision to increase the tariffs is not something that we intend to do within this 90 day period."

Part A of the list includes products worth €2.8 billion, which the EU can target with tariffs of 25 percent at any moment after notifying the list to the WTO, the official said.

Part B lists those products which would only be targeted after three years. This is because World Trade Organization rules allow immediate retaliation only on that amount of trade for which EU steel exports to the U.S. have not increased over the past years. "We are certainly playing this by the book," the official said.