Top advisers to President Donald Trump met at the White House late last week to consider possible steps, including military action, as officials spoke of "credible threats" by Iran or Iranian proxy forces to U.S. personnel. The Pentagon already has moved an aircraft carrier, strategic bombers and other military assets to reinforce U.S. forces across the Middle East.
Officials said the options include increasing the number of troops in the region from between 60,000 and 80,000 to more than 100,000, in the most dramatic scenario were Iran to attack U.S. interests or make clear moves to develop a nuclear weapon.
The New York Times on Monday reported that acting defense secretary Patrick Shanahan, in response to a request for updated options from national security adviser John Bolton, put forward several proposals, including one to deploy 120,000 troops.
Speaking to reporters in Washington, Trump characterized the article as inaccurate but said he would be prepared to authorize an even more muscular approach if needed.
"Hopefully we're not going to have to plan for that," he said. "And if we did that, we'd send a hell of a lot more troops than that."
Trump's views on the proposals were not immediately clear. In general, he has sided with ending U.S. military involvement in wars overseas, although he has identified Iran as a chief adversary and sought to demonstrate a tough stance on nations challenging the United States. He is surrounded by officials with hard-line views on Iran led by Bolton, who has advocated for regime change in Iran.
Iranian and American leaders say they do not want a war but warn that they are prepared to use military might if provoked. Speaking during a visit to Sochi, Russia, on Tuesday, Secretary of State Mike Pompeo said he had made clear "that if American interests are attacked, we will most certainly respond in an appropriate fashion."
Iran's supreme leader, Ayatollah Ali Khamenei, in a series of messages on Twitter, warned that the United States would be forced to withdraw from a confrontation with Iran. "We don't seek a war nor do they," he said. "They know a war wouldn't be beneficial for them."
Nevertheless, the increasing tension has fueled concern that the two countries might accidentally slide into conflict. The comments from Khamenei and Pompeo came several days after ships belonging to U.S. allies were attacked near the Persian Gulf, an act for which U.S. officials suggested Iran may be responsible. The incident followed a series of U.S. steps designed to isolate Iran, including the designation of its Islamic Revolutionary Guard Corps as a terrorist organization and a raft of new sanctions after the White House decision to pull out of the 2015 nuclear deal.
Becca Wasser, a policy analyst at Rand Corp., said those steps fueled suspicions between the United States and its allies on one hand and Iran on the other, raising the risk of a small incident snowballing into a larger confrontation.
"It's fairly common to have Iranian patrol boats harass U.S. carriers and other ships in the strait," she said, referring to the Strait of Hormuz, a waterway off Iran that is key to global commerce. "You can imagine with some of the heightened tensions, that there could be a greater risk of that exploding into something larger."
"In different times, an accident or a mistake could be resolved because of open lines of communication between Iran and the United States," she added. "Now it could lead to the United States and Iran accidentally stumbling into some form of escalation."
Typically a range of options is presented by military officials when requested by civilian leaders. Sometimes, policymakers select one course of action. Other times, they decide to do nothing.
U.S. Central Command maintains a host of contingency plans that are updated periodically, especially when policy or threat information changes.
Military officials, who have privately voiced a strong desire to avoid conflict with Iran, have nevertheless described the recent intelligence as sobering and say they believe that Iran is actively planning attacks on U.S. forces.
Capt. Bill Urban, a spokesman for U.S. Central Command, said the alert level for forces in Iraq and Syria had been increased in response to the recent intelligence, pushing back against a statement by a British general serving in Baghdad as part of the U.S.-led coalition who said there was no amplified threat from Iranian backed forces there. That operation "is now at a high level of alert as we continue to closely monitor credible and possibly imminent threats to U.S. forces in Iraq," Urban said.
More than 5,000 U.S. troops are in Iraq, and less than half that are in neighboring Syria.
The U.S. military has troops at a constellation of small and large bases across the region as well as ships that regularly circulate nearby.
Pentagon and congressional officials said the elements that contributed to the worrisome intelligence picture included Iranian military and other threats against diplomatic facilities in Baghdad and Irbil, Iraq. Officials also said they believed that Iran may be preparing to mount rocket or missile launchers on small ships.
Military officials say they do not know why Iran appears to be embracing a more hostile stance but say it is probably a result of mounting economic and diplomatic pressures.
Since the United States withdrew from the nuclear agreement a year ago, it has penalized almost 1,000 Iranian individuals and entities. U.S. sanctions on financial transactions and oil exports, in particular, have had a devastating effect on the economy.
International nuclear monitors have said that Iran has continued to meet its commitments under the 2015 agreement but that it has threatened to resume the stockpiling of enriched uranium unless the European Union finds a way to facilitate sanctions relief. The Europeans, while striving to keep the nuclear accord alive, are stuck between the hard-line positions staked out by Washington and Tehran.
The uptick in tensions has also rattled the State Department's top officials in charge of diplomatic security, who on Tuesday postponed a major forum of regional security officers from most embassies and consulates worldwide. The event, which was scheduled to include Pompeo; Rep. Michael McCaul of Texas, the top Republican on the House Foreign Affairs Committee; and Sen. Tim Kaine, D-Va., was postponed because of "increasing tensions with Iran" and the need for senior personnel to "remain in the field to assess and respond to potential threats," according to a State Department memo obtained by The Washington Post.
The event is scheduled every three to four years and involves 300-plus people, said a State Department official, who spoke on the condition of anonymity because he was not authorized to discuss internal logistics. "It's no small potatoes that Diplomatic Security chose to cancel this," the official said.
The situation has set off alarm bells on Capitol Hill, where Senate Majority Leader Mitch McConnell, R-Ky., is attempting to bring in senior administration officials to brief senators next week on Iran and other issues in the region, according to three congressional officials apprised of the discussions.
The effort comes as many lawmakers are voicing their frustration with the Trump administration for not keeping Congress more fully aware of its plans concerning Iran.
"I think all of us are in the dark over here," Sen. Lindsey Graham, R-S.C., a member of the Senate Foreign Relations Committee, said Tuesday.
Democrats on that committee in particular have accused their Republican counterparts of dragging out efforts to demand more information from the White House.
"It is hard to justify the administration's actions thus far since they insist on stonewalling Congress from receiving any specifics about what these increased threats actually are and our strategy to confront them," Sen. Robert Menendez of New Jersey, the top Democrat on the committee, said in a statement Tuesday.