Including exemptions for key allies is a softening of the administration's previous indications that the rules would apply uniformly.
"We are not the players we once were in steel and aluminum, and whether or not we can invoke enough pain, that would give Trump a negotiating lever we don't know", said Blessing.
President Donald Trump today imposed heavy tariffs on imported steel and aluminium which he said were necessary to boost the U.S. industry suffering from "unfair" business practices, a move that has sparked fears of a global trade war.
With the new tariffs set to take effect in 15 days, Trump left room for exemptions for other countries, saying, "I'll have a right to drop out countries or add countries".
"These measures could make a significant impact on the economic and cooperative relationship between Japan and the USA, who are allies", Taro Kono, Japan's foreign minister, said in a statement. Trump said the order would temporarily exempt Canada and Mexico, pending discussions with both about the terms of trade, including already tense talks over the North American Free Trade Agreement.
Prime Minister Malcolm Turnbull had been lobbying Mr Trump in a bid to secure an exemption for Australia. Australian steel exports to the U.S. are less than 0.1% of GDP but the prospect of local exporters losing the United States market was a source of concern.
Trump is not the only USA president in recent history to impose global tariffs on imports.
Trump's confirmation that there is room from exemptions is a significant weakening of the administration's position on the weekend.
Congressional Republicans and business groups are bracing for the impact of the tariffs, appearing resigned to additional protectionist trade actions as Trump signals upcoming economic battles with China. Several spoke of how excessive "dumping" of steel and aluminum imports had negatively affected their jobs and families.
South Korea's trade minister, speaking at an emergency meeting, appealed to other governments to prevent a "trade war".
Trump cited the close relationship between the three countries, including national security ties, as justification for the decision.
The tariffs would "seriously impact the normal order of worldwide trade", China's commerce ministry said.
McConnell and Ryan noted that Trump had given a loophole to some allies, but indicated they are concerned they don't go far enough.
The House speaker's condemnation was swiftly echoed by other top Republicans in Congress, who fear the tariffs could spark a trade war and hurt the U.S. economy. Decades, in fact, by unfair foreign trade practices, leading to the shuttered plants and mills, the laying-off of millions of workers, and the decimation of entire communities.