Trump left the door open to trading partners Canada and Mexico, as well as military allies, being exempt from the measures.
"I have to think that the exclusion was probably also granted because we're going to be a little more accommodating to them at the (NAFTA) negotiating table", said Mark Warner, a Canadian trade lawyer.
Australian Chamber of Commerce and Industry chief executive James Pearson said Australia must now use its diplomatic skills to help to avert a global trade war that no one will win. Talks would continue next week. Trump tweeted that he spoke with Japanese Prime Minister Shinzo Abe, saying they are "discussing opening up Japan to much better trade with the U.S. now have a massive $100 Billion Trade Deficit".
Other countries that present an alternative way to address the USA national-security threat of their exports may be exempt as well.
At a press conference after the talks, Seko said: "Mr. Lighthizer provided an explanation of the upcoming process and schedule". "Any type of trade war. hurts us as an American company", Harris said. "We will look at the impact onJapanese businesses and make a final decision".
Citing Chinese researchers, Zhong said the USA has been overstating its trade deficit with China by about 20 percent every year.
In terms of employment, the same argument goes that the number of American jobs to be lost in other industries because of the higher steel prices would be greater than that of workers to be added to the steel sector.
Failing to include the national security adviser in talks on tariffs would seem highly unusual, given Trump's argument that weakened U.S. steel and aluminum industries would threaten national security.
Lighthizer was expected to be in Brussels this weekend for meetings with European and Japanese trade officials.
The visit had been planned for weeks as a follow-up discussion on over capacity, seen by observers as a swipe at China.
Trade tensions between China and United States have risen since Trump took office. President Trump should now focus on protecting the entire manufacturing supply chain through broader trade remedies, including efforts to address currency exchange issues.
The 28-nation European Union, which negotiates trade policy as a bloc, has warned it will challenge the tariffs at the World Trade Organization.
Australia is heavily involved in supporting US-led operations internationally and spends 2 percent of its GDP on defence - more than most allies - much of which is spent on US-made defence equipment.
Trump on Friday said Australia would become the third country to be free from a 25 percent tariff on steel imports and 10 percent for aluminum.
It has already started monitoring incoming metal flows to see whether a surge occurs.
The EU is also maintaining a threat of countermeasures that would target United States imports ranging from corn to motorcycles, and might publish its list next week to allow industry and other interested parties to give their input.
Brussels has pushed back the hardest against Washington's shock measures, loudly announcing a list of United States products - including peanuts and motorcycles - it could hit with countermeasures.