The United States is deploying a Patriot missile battery and another warship to the Middle East to counter what it claims are growing threats from Iran.
The USS Arlington, an amphibious transport ship, and a Patriot air defense system will be deployed to the U.S. Central Command.
"The United States does not seek conflict with Iran, but we are postured and ready to defend U.S. forces and interests in the region," the Department of Defense said in a statement on Friday announcing the moves.
National Security Adviser John Bolton said last Sunday that the U.S. was sending a carrier strike group and a bomber task force to the region to send a "clear and unmistakable message" to Tehran. The Pentagon said the latest deployment followed that original request.
The decision to surge additional military forces into the Middle East was based in part on intelligence that the Iranian regime has told some of its proxy forces and surrogates that they can now go after American military personnel and assets in the region, three U.S. officials familiar with the intelligence told NBC News.
The three officials said that in addition to learning that an Iranian official had discussed attacks on Americans, the U.S. began seeing the movement of Iranian and Iranian-backed forces in various places across the region, prompting the commander of U.S. Central Command, Marine Corps Gen. Frank McKenzie, to request additional forces move to the region.
The Pentagon's statement on Friday said the new deployment was "in response to indications of heightened Iranian readiness to conduct offensive operations against U.S. forces and our interests."
The strike group deployed earlier in the week consists of the USS Abraham Lincoln, a Nimitz-class aircraft carrier; the USS Leyte Gulf, a Ticonderoga-class guided missile cruiser; Carrier Air Wing Seven; and destroyers from Destroyer Squadron Two.
Acting Secretary of Defense Patrick Shanahan tweeted Monday calling on the Iranians to "cease all provocation," warning that the United States "will hold the Iranian regime accountable for any attack on U.S. forces or our interests."
Iran's ambassador to the United Nations denied that Tehran gave the green light to its proxies to attack U.S. forces.
In an exclusive interview with NBC News on Thursday, Ambassador Majid Takht Ravanchi rejected statements from the Trump administration that Tehran posed a heightened danger to U.S. interests and accused U.S. officials of employing "fake intelligence."
President Donald Trump said on Thursday that he was ready to speak with Iranian leaders and come to an understanding that would allow the country to improve its economic prospects.
"What I'd like to see with Iran, I'd like to see them call me," he said.
Trump added: "I look forward to the day where we can actually help Iran. We're not looking to hurt Iran."
Amid the mounting pressure from Washington, Iran on Wednesday informed ambassadors from the United Kingdom, France, Germany, China and Russia that it would stop implementing parts of the landmark 2015 nuclear deal.
In a speech broadcast on national television on the anniversary of America's withdrawal from the deal, President Hassan Rouhani said the country would also resume high level enrichment of uranium if world powers did not keep their promises under the Obama-era agreement.
The Trump administration has previously acknowledged that Iran was living up to the agreement, but alleges it also gave the Islamic republic cover to pursue its ballistic weapons program and deepen its regional influence.
Washington subsequently restored crippling sanctions on Iran, exacerbating a severe economic crisis.