Trump said the measures were necessary to balance global trade deficits.
"The United States has been taken advantage of by other countries, both friendly and not so friendly," Trump said during a news conference with his Swedish counterpart.
The President said he didn't blame individual countries but instead past presidents for allowing trade deficits to balloon.
"I don't blame the countries," he said. "I blame our leadership for allowing it to happen."
He singled out the European Union in particular, saying barriers on trade made it difficult for US goods to enter the bloc.
"The European Union has been particularly tough on the US. they make it almost impossible for us to do business with them," he said.
Earlier Tuesday, Trump attempted to rebut claims that his West Wing is rattled with disorder and low morale. But his message on Twitter only heightened speculation that some aides may soon depart the White House.
"The new Fake News narrative is that there is CHAOS in the White House. Wrong!" Trump wrote. "People will always come & go, and I want strong dialogue before making a final decision. I still have some people that I want to change (always seeking perfection). There is no Chaos, only great Energy!"
The news conference also provided Trump an opportunity to weigh in on upcoming talks between North and South Korea, which were announced Tuesday. Trump has said talks between the US and North Korea must only begin after Pyongyang agrees to denuclearization.
Unlike the United States, Sweden has a diplomatic relationship with North Korea. Prime Minister Stefan Löfven has offered to assist the United States in its efforts to end the nuclear crisis there.
Löfven is the first European leader to visit the White House since Trump announced he would slap stiff new tariffs on steel and aluminum last week. The European Union has vowed to take reciprocal action, and European Commission President Jean-Claude Juncker discussed the matter with Löfven before he arrived in Washington, according to Swedish news agencies.
Trump hit back at the EU on Saturday during closed-press remarks to donors at his Mar-a-Lago estate in Florida.
"I will tell you the European Union -- brutal. They've been brutal to us," Trump said.
He wrote on Twitter later that if the EU increases tariffs on US goods "we will simply apply a Tax on their Cars which freely pour into the U.S. They make it impossible for our cars (and more) to sell there. Big trade imbalance!"
The remark alarmed European automakers, including Sweden's Volvo.
Final details of the tariff plan aren't yet known, and foreign allies have been lobbying Trump over the phone to narrow the scope of his trade decision. Trump will meet with Swedish business representatives midday Tuesday before his news conference.
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