VOA's Carla Babb contributed to this report.
U.S. lawmakers expressed sharply diverging opinions on the threat level posed by Iran after classified briefings President Donald Trump's national security team presented to all House and Senate members Tuesday.
"They explained to us how the Iranian threat streams were different than in the past … and that attacks against American interests and personnel were imminent," Republican Sen. Lindsey Graham of South Carolina told reporters after meeting behind closed doors with Secretary of State Mike Pompeo, acting Defense Secretary Pat Shanahan, and Joint Chiefs of Staff Chairman Gen. Joseph Dunford.
"There was an escalation by Iran and its proxies," said the top Republican on the House Foreign Affairs Committee, Michael McCaul of Texas. "We're obviously concerned about our military soldiers who are threatened by Iran, and a potential attack on them in Iraq, specifically."
Democrats had a different take on the briefings, as well as the wisdom of the Trump administration's pressure campaign against Iran's government and its proxies in the Middle East.
"I heard nothing that wasn't a regurgitation of past administration talking points on Iran. It was a long, lengthy history of their many transgressions … so far, not a single shred of evidence to justify the escalation of tensions in the region," Virginia Democratic Rep. Jerry Connolly said.
"This briefing was all about tactics, not about strategy. And that's been our worry from the beginning — that this is blind escalation," Democratic Sen. Chris Murphy of Connecticut said.
Shanahan disputed such characterizations in comments to reporters at the Capitol.
"I walked them [lawmakers] through what the Department of Defense has been doing since May 3, when we received credible intelligence about threats to our interests in the Middle East and to American forces, and how we acted on that credible intelligence," the acting defense secretary said. "We have deterred attacks based on our reposturing of assets, deterred attacks against American forces."
Earlier in the day, a Pentagon spokesman told VOA that U.S. intelligence points to Iran as "highly likely responsible" for recent attacks on four oil tankers in the Persian Gulf.
The Pentagon has deployed the USS Abraham Lincoln aircraft carrier strike group, the USS Arlington landing platform dock ship, a Patriot missile battery and B-52 bombers to the region.
The U.S. Navy's Fifth Fleet said it has increased maritime patrols and exercises in the Arabian Sea that highlight the "lethality and agility to respond to threat."
Iran, meanwhile, has announced a quadrupling of its uranium enrichment capacity, threatened to move closer to weapons-grade enrichment absent relief for its battered economy, and rejected, for now, any prospect of dialogue with Washington.
Iranian Foreign Minister Mohammad Javad Zarif decried what he termed "genocidal taunts" by the Trump administration, adding that "Iranians have stood tall for a millennia, while aggressors [have] all gone," including Genghis Kahn and Alexander the Great.
"Try respect. It works," Zarif tweeted.
Tehran's responses to America's pressure campaign should give the Trump administration pause, according to Murphy.
"The Iranians are nowhere near being ready to talk. They are not showing any signs of backing down from their provocative behavior. So, tell me how this [Trump administration] strategy is working if Iran won't talk and they're not deescalating militarily," the Democratic senator said. "I don't think they [administration officials] have any good answers. Their plan is to just continue to push and push and push, and hope that eventually the Iranians change their mind."
Republicans argued that pressure on Iran is wise and warranted to protect Americans serving in the Middle East.
"We owe it to those in theater who are doing our bidding as a nation to make sure that nobody can attack them without thinking twice about it. And deterrence is best had by moving military assets forward to make it real to Iran," Graham said. "This is a very measured response. We've been attacked for years by Iran. For 40 years, they have been killing people, including Americans. Now, we are at a point in time when we're pushing back against the regime."
Trump pulled out of the 2015 international nuclear agreement with Iran one year ago. He reimposed sanctions on Tehran and has threatened other penalties on countries that still do business with Iran. Washington's actions have made the Iranian economy, already in tatters, even weaker.