"It's clear. We need clarity", European Commission Vice President Jyrki Katainen said on Friday.
Tokyo and Brussels rejected any suggestion that their exports to the United States threatened the country's national security - Trump's justification for imposing the tariffs despite warnings at home and overseas that they could provoke a global trade war.
A top trade official in the European Union warned the White House on Thursday that it has an "arsenal" of measures at its disposal to fight back against President TrumpDonald John TrumpAccuser says Trump should be afraid of the truth Woman behind pro-Trump Facebook page denies being influenced by Russians Shulkin says he has White House approval to root out "subversion" at VA MORE's planned tariffs on steel and aluminum imports.
Brussels has prepared a list of U.S. products to hit with countermeasures if its exports are affected by the tariffs, but says it hopes to join Canada and Mexico in being exempted.
Brussels is also looking at "safeguard" measures to protect its industry - restricting the bloc's imports of steel and aluminium to stop foreign supplies flooding the European market, which is allowed under World Trade Organisation rules.
Japan, the United States' top economic and military ally in Asia, is among the other nations seeking to join the exemption list.
China's steel and metals associations urged the government to retaliate, citing imports from the U.S. ranging from stainless steel to coal, agricultural products and electronics. Chief Cabinet Secretary Yoshihide Suga told a news conference that Japan's steel and aluminium shipments posed no threat to USA national security.
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Secretary of State Rex Tillerson that ties between the two countries were closer than during the previous U.S. administration. Kushner, who is Trump's son-in-law, and the other USA officials also attended an earlier separate meeting with Videgaray.
Lighthizer's meetings with European Union trade chief Cecilia Malmstrom and separately with Japanese Trade Minister Hiroshige Seko were long planned, but they took on added urgency as allies warned the United States moves could provoke a global trade war. "Europe is certainly not a threat to American internal security so we expect to be excluded", European Trade Commissioner Cecilia Malmstrom said in Brussels. Under WTO rules, the European Union can retaliate in a proportionate manner if they do not receive compensation for new trade restrictions within 90 days.
German Chancellor Angela Merkel urged dialogue and warned that "no one can win in such a race to the bottom".
The target of Trump's ire is China, whose capacity expansions have helped add to global surpluses of steel.
"We want Congress to understand that this would be a lose-lose situation", he said.
"This is not a trade negotiation", Katainen said.
Trade tensions between Washington and Beijing have risen since Mr Trump took office a year ago.
The dispute has fuelled concerns that soybeans, the United States' most valuable export to China, might be caught up in the row after Beijing launched an inquiry into imports of USA sorghum, a grain used in animal feed and liquor.