Defense Secretary Ash Carter says the United States is “concerned” that Iranian ships may be carrying advanced weapons for the Shi’ite Huthi rebels in Yemen.
"There's no reason for anybody to be delivering advanced weapons into a situation that's already gotten way beyond what is reasonable there," Carter told reporters on April 22.
The comments follow reports that nine Iranian ships were heading toward Yemen, possibly carrying arms for the Huthis. Such shipments would be in violation of a UN Security Council resolution.
The White House said the aircraft carrier USS Theodore Roosevelt was also heading to waters off the coast of Yemen, joining other U.S. warships, to ensure freedom of navigation and commerce.
Asked whether the United States might attempt to forcibly stop and board one of the Iranian ships if it tries to crossed into Yemen, Carter said, “We have options."
"We're not at that point,” he added. “We're at the point of trying to get the parties back to the table."
Carter also said that Washington is making it clear to Tehran that "obviously fanning the flames or contributing to it by any party is not welcome to us."
On April 21, President Barack Obama warned Iran against delivering weapons to Yemen that could be used to threaten shipping traffic in region.
"We've been actually very straightforward to them," Obama said in an MSNBC interview.
Iran denies providing military assistance to the rebels.
Meanwhile in Yemen, Saudi-led coalition jets have bombed Huthi rebels, hours after announcing the end of a bombing campaign against them.
Reports said the strikes outside the third city of Taiz on April 22 followed the fall of a base of an army unit loyal to President Abd-Rabbu Mansur Hadi.
Fighting was also reported in the second city of Aden and elsewhere.
The Saudi ambassador to the United States, Adel al-Jubeir, warned that Riyadh will respond if rebels carry out any "aggressive moves."
The rebels demanded the coalition end its attacks as a condition for UN-sponsored talks.
On April 21, the coalition of Sunni Arab nations declared its monthlong bombing campaign, which sought to restore President Hadi, had achieved its goals.
Spokesman Brigadier General Ahmed Asseri said a new, more limited operation is to focus on preventing the rebels from "targeting civilians or changing realities on the ground" and finding a political solution the conflict.
Iran described the decision as a positive development and called for peace talks.
The UN says more than 1,000 people have been killed in Yemen since the air strikes began.
The Huthi rebels took control of Yemen’s capital, Sanaa, in January, and President Hadi later took refuge in Aden.
Hadi left the country in March when the Huthis, backed by army units supporting former President Ali Abdullah Saleh, reached the southern port city.
With reporting by AP, Reuters, and AFP