The escalation was only one element of a tougher foreign policy posture — at least in some areas — by the administration in recent days. Senior officials gave new emphasis to President Trump’s willingness to use force in Venezuela, and Trump on Monday doubled down on his threat to impose vast new trade penalties against China.

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But Iran appeared to be the main focus of administration action. U.S. officials have said they are not seeking war with Iran but rather are applying “maximum pressure” to change “malign” Iranian behavior in the region.

Since withdrawing from the Iran nuclear agreement last year, the Trump administration has imposed sanctions on purchasers of Iranian oil and designated the Islamic Revolutionary Guard Corps, a branch of the Iranian military, a terrorist group. On Friday, the State Department announced new restrictions on Iran’s civil nuclear program.

The program is allowed under the nuclear deal, which is still supported by signatories Britain, France, Germany and the European Union, in addition to Russia and China. The European allies on Saturday cried foul and issued a sharply worded statement emphasizing their “continued commitment” to the deal.

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Although the Iranian government did not respond directly to the latest U.S. move, its tightly controlled media said that President Hassan Rouhani would unveil countermeasures to the array of administration measures in a Wednesday speech marking the anniversary of the U.S. withdrawal from the nuclear accord.

Mehr news agency, quoting an “informed source,” said it was unlikely that Rouhani would announce a full withdrawal from the agreement. In the past, Iran has threatened to limit access for the International Atomic Energy Agency’s monitors.

Another possible option, said Dennis A. Ross, who participated in U.S. negotiations in the Middle East through a number of administrations, would be to enrich a small amount of uranium to 20 percent — more than five times the level allowable under the agreement — to provide fuel for a research reactor that the United States has now sanctioned. It would be a technical violation of the agreement, Ross said, but the Iranians would present it as, “We haven’t been left any choice.”

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Ilan Goldenberg, a former State Department and Pentagon official who worked on Middle East issues, said any Iranian decision to launch or authorize direct anti-American attacks would be a departure from the cautious stance it has taken in the past few years. Tehran, for example, has sharply curtailed its naval forces’ harassment of American ships in the Persian Gulf, he said.

The White House and the State and Defense departments declined to specify the nature of the new threats from Iran. Acting defense secretary Patrick Shanahan said in tweets that he approved a request for the deployments from the top U.S. general overseeing military operations in the region.

Shanahan described it as a “prudent repositioning of assets in response to indications of a credible threat by Iranian regime forces” and called on Iran to “cease all provocation.”

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“We’ve been tracking a variety of threat streams for some time,” but the U.S. Central Command recently detected “specific and credible” information that differed from those previous threats, said a defense official, who spoke on the condition of anonymity because they were not authorized to speak publicly on the matter. The threats involved Iranian military forces and proxy forces and indicated potential actions against U.S. military personnel and nonmilitary interests on both land and sea, the official said.

Asked about new threats, Secretary of State Mike Pompeo referred to Iraq, saying that he had “a responsibility to keep the officers that work for me safe. . . . That includes in Irbil and Baghdad . . . all around the Middle East.”

The United States has a diplomatic presence and more than 5,000 troops in Iraq. An additional 2,000 U.S. forces are in neighboring Syria, and thousands of American forces are based at air, land and sea installations in Qatar, Kuwait and Bahrain, as well as at small installations in Saudi Arabia.

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Karim Sadjadpour, an Iran expert with the Carnegie Endowment for International Peace, wrote last week in the Atlantic that Arab officials in the Persian Gulf “claim to have picked up intelligence indicating that Tehran is planning to agitate against them in the region, via proxy.”

A leading Israeli journalist, Barak Ravid of Israel’s channel 13 news, reported Monday that Israel had passed on information about an alleged Iranian plot to strike U.S. interests in the Persian Gulf. An Israeli Embassy spokesman declined to comment on the report.

The aircraft carrier Abraham Lincoln and its associated escort ships are in the Mediterranean and have been en route to the Persian Gulf region since early April. Becca Wasser, who studies the Middle East for the Rand Corp., said the deployment announcement, which will speed the ship’s arrival, appeared designed to “leverage” an already planned deployment and send a message to Iran.

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Among those who expressed skepticism of the administration’s still-veiled reasons for the deployments, Sen. Tom Udall (D-N.M.) charged that Trump’s “team of saber-rattling foreign policy advisers are all but openly shouting their desire for an unauthorized and unconstitutional war with Iran, needlessly putting American troops and their families at risk . . . Congress must act immediately to stop this reckless march to war before it is too late.”