(CNN) The Pentagon and US intelligence agencies are closely tracking two Iranian ships that Tehran claims are bound for Venezuela.
At the Pentagon and other agencies, officials said that at the moment the ships' passage is not a concern, but they are being monitored and the intelligence community is working to assess what Iran's intentions are. The two countries -- both the subject of harsh US sanctions -- are allies and trading partners that have helped each other withstand the American measures.
While it is still unclear if the ships are carrying any weapons, according to multiple US officials, satellite imagery reveals one of them is carrying the kind of small, fast-attack boats that Iran has used to harass US naval ships in the Persian Gulf. And if Iranian vessels gain the ability to access the Atlantic, analysts say it would be a significant step forward for the country's navy, which has tried and failed to do so in the past.
Officials said the US has been monitoring the ships for approximately two weeks. The vessels have been off the east coast of Africa for the past several days. While they were initially expected to round the Cape of Good Hope at the southern tip of the continent around June 9 to June 11, experts tracking their movement say that now they are not expected to arrive until July.
Pentagon spokesman John Kirby, speaking generally about the possibility of any shipment of Iranian weapons to the Western Hemisphere, said that would be a "provocative act" and a threat to US allies.
"While DoD will not comment on intelligence matters, we would note that the delivery of such weapons would be a provocative act and a threat to our partners in this hemisphere. As such we would reserve the right to take appropriate measures -- in concert with our partners -- to deter the delivery or transit of such weapons," Kirby said in a statement to CNN.
On Wednesday, the semiofficial Mehr news agency reported that the deputy head of the national security and foreign policy commission of Iran's Parliament had said that "the threat of Iranian vessels is a violation of international law, and if it continues in this way, the US Navy will certainly be in danger, and we can threaten American vessels in the waters of the region."
One of the Iranian ships, a floating base named Makran, was seen in late April in satellite images from Maxar Technologies in the port of Bandar Abbas with seven small fast-attack boats on its deck. A smaller frigate is accompanying the Makran. Politico was first to report US concern about the ships.
The US concern is if the Iranians transfer the attack boats to Venezuela. These fast, agile vessels are often used by Iran's Islamic Revolutionary Guard Corps in the Persian Gulf to swarm commercial or military shipping, including US Navy and Coast Guard ships operating there. They can be equipped with a variety of weapons ranging from small arms, anti-ship missiles and torpedoes.
Officials stress that they are unsure if weapons are on board either of the Iranian ships. "The concern would be these are missile attack boats," one defense official said. "That type of weapon is something we would not want close to our shores."
There is some uncertainty about the ships' course. A US official told CNN that in recent days, they have sailed in a confusing manner that has observers wondering whether they will proceed on course for the Atlantic.
As the US tries to gauge Iran's intentions, two sources say one working theory is that Iran is trying to tout its ability to operate in the Atlantic -- a "hey, we are here and present" statement. Both officials emphasized that the warship and the accompanying frigate are not a big concern for now and there is hope that Iran will find a face-saving way to turn them around and send them home.
"This is not a Navy designed for blue water operations," one of the defense officials said. The US military generally refers to "blue water" navies as those that can readily operate in open ocean at great distances from their home nations and support operations for extended periods.
For now, US officials are watching to see if any ports allow the ships entry for fuel and resupply before they attempt to cross the Atlantic. The US believes they could have trouble making such a long journey.
The potential journey into the waters of the Atlantic Ocean would mark a step forward for Iran's Navy, said Behnam Ben Taleblu, who watches the Iranian military for the Foundation for Defense of Democracies think tank. Taleblu and others are watching the Makran closely because of a promise Iran made in 2016 to develop naval capability in the Atlantic Ocean. An attempt to sail ships around Africa that same year ended in failure, Taleblu said, when the ships had to make an emergency stop in Durban, South Africa, cutting short the effort.
"If this trip is successful ... it doesn't mean Iran will have a blue water navy right away, but it could represent a significant evolution in Iran's conventional Navy, which has atrophied compared to the elite Revolutionary Guard Corps," he said. Iranian officials have touted the Makran as an expeditionary forward base, a platform from which they could launch suicide drones, helicopters, attack craft and the like, Taleblu said.
In a thinly veiled criticism, Kirby placed the blame for Iran's actions on the Trump administration and its maximum pressure campaign of sanctions against Iranian officials. Instead, Kirby stressed the diplomatic efforts, in coordination with US allies, to rein in Iran's nuclear activities.
"This is a situation that the current administration inherited, and like many things with respect to Iran -- including its rapidly expanding nuclear program absent the limits imposed by the [Iran nuclear deal] -- we are now working to forestall through diplomacy and other means," he said.