The proposal includes more aggressive U.S. interceptions of Iranian arms shipments such as those to Houthi rebels in Yemen and Palestinian groups in Gaza and Egypt’s Sinai, a current official and a knowledgeable former U.S. official said.

The plan also recommends the United States react more aggressively in Bahrain, whose Sunni Muslim monarchy has been suppressing majority Shi’ites, who are demanding reforms, the
sources said.

In addition, U.S. naval forces could react more forcefully when harassed by armed speed boats operated by the Islamic Revolutionary Guard Corps, Iran’s paramilitary and espionage contingent, three of the sources said.

U.S. ships have fired flares and warning shots to drive off IRGC boats that made what were viewed as threatening approaches after refusing to heed radio warnings in the passageway for 35 percent of the world’s seaborne petroleum exports.

U.S. commanders now are permitted to open fire only when they think their vessels and the lives of their crews are endangered. The sources offered no details of the proposed changes in the rules, which are classified.

The plan does not include an escalation of U.S. military activity in Syria and Iraq. Trump’s national security aides argued that a more muscular military response to Iranian proxies in Syria and Iraq would complicate the U.S.-led fight against Islamic State, which they argued should remain the top priority, the sources said.

Mattis and McMaster, as well as the heads of the U.S. Central Command and U.S. Special Forces Command, have opposed allowing U.S. commanders in Syria and Iraq to react more forcefully to provocations by the IRGC, Hezbollah and other Iranian-backed Shi’ite militias, all five sources said.

The advisers are concerned that more permissive rules of engagement would divert U.S. forces from defeating the remnants of Islamic State, the sources said.

Moreover, looser rules could embroil the United States in a conflict with Iran while U.S. forces remain overstretched, and Trump has authorized a small troop increase for Afghanistan, said the second senior administration official.

Another former U.S. official said Hezbollah and Iranian-backed Shi’ite militias in Iraq have been “very helpful” in recapturing vast swaths of the caliphate that Islamic State declared in Syria and Iran in 2014.

U.S. troops supporting Kurdish and Sunni Arab fighters battling Islamic State in Syria have been wrestling with how to respond to hostile actions by Iranian-backed forces.

In some of the most notable cases, U.S. aircraft shot down two Iranian-made drones in June. Both were justified as defensive acts narrowly tailored to halt an imminent threat on
the ground.

Trump’s opposition to the 2015 Iran nuclear deal, known as the Joint Comprehensive Plan of Action (JCPOA), poses a dilemma for policymakers.

Most of his national security aides favor remaining in the pact, as do U.S. allies Israel and Saudi Arabia despite their reservations about Iran’s adherence to the agreement, said U.S. officials involved in the discussions.

“The main issue for us was to get the president not to discard the JCPOA. But he had very strong feelings, backed by (U.S. Ambassador to the United Nations) Nikki Haley, that they should be more aggressive with Iran,” one of the two U.S. officials said. “Almost all the strategies presented to him were ones that tried to preserve the JCPOA but lean forward on these
other (issues.)