WASHINGTON — Iran is building a nonworking mock-up of a U.S. nuclear-powered aircraft carrier that U.S. officials say may be intended to be blown up for propaganda value.

Intelligence analysts studying satellite photos of Iranian military installations first noticed the vessel rising from the Gachin shipyard, near Bandar Abbas on the Persian Gulf, last summer. The ship has the same distinctive shape and style of the Navy’s Nimitz-class carriers, as well as the USS Nimitz’s No. 68 neatly painted in white near the bow. Mock aircraft can be seen on the flight deck.

The Iranian mock-up, which U.S. officials described as more like a barge than a warship, has no nuclear-propulsion system and is only about two-thirds the length of a typical 1,100-foot-long Navy carrier. Intelligence officials do not believe that Iran is capable of building an actual aircraft carrier.

“Based on our observations, this is not a functioning aircraft carrier; it’s a large barge built to look like an aircraft carrier,” said Cmdr. Jason Salata, a spokesman for the Navy’s 5th Fleet in Bahrain, across the Persian Gulf from Iran. “We’re not sure what Iran hopes to gain by building this. If it is a big propaganda piece, to what end?”

Whatever the purpose, U.S. officials acknowledged Thursday that they wanted to reveal the existence of the vessel to get out ahead of the Iranians.

Navy and other U.S. intelligence analysts surmise that the vessel, which 5th Fleet wags have nicknamed the Target Barge, is something that Iran could tow to sea, anchor and blow up — while filming the whole thing to make a propaganda point, if, say, the talks with the Western powers over Iran’s nuclear program go south.

Iran has previously used barges as targets for missile firings during training exercises, filmed the episodes and then televised them, Navy officials said.

But unlike Iran’s efforts to conceal its underground nuclear-related sites, the Iranian navy has taken no steps to cloak from prying Western satellites what it is building pierside at the busy shipyard.

When the mock-up will take its maiden voyage — if it ever does — is anyone’s guess, analysts said. The vessel is nearing completion, they said, and will presumably be shipped by rail on tracks that run through the shipyard, to its destiny in the Persian Gulf just a few hundred yards away.