WASHINGTON (CNN) -- The U.S. military and intelligence community have been tracking several shipments of material they believe have left North Korea and are destined for Syria or may have already landed there, a Pentagon official confirmed.
Israeli soldiers deployed in the Golan Heights look toward Syria on September 7.
The monitoring has been taking place for the past several weeks, he said.
The official could not confirm several recent news reports that nuclear material from North Korea has arrived in Syria and was the potential target of a recent Israeli airstrike there.
In fact, he said none of the information he had reviewed as part of his job indicated any nuclear material was involved.
Some of the material is believed to have been high-grade metals that could be used in weapons such as missiles or solid-fuel rocket technology.
But "there is concern with shipments going into the region and with their eventual arrival in Syria," the official said.
The United States is also looking into the possibility material had been shipped from North Korea to Iran and traveled overland into Syria, he said, adding there were indications a ship had docked in Syria recently.
"Shipments have landed we are concerned about," he said.
The Syrians have been talking to the North Koreans about buying solid-fuel rocket technology for their missiles and those shipped to Hezbollah, other analysts said. That development would pose an increased risk to Israel.
But it's not clear these shipments are in fact tied to the recent Israeli airstrike in northern Syria against a facility that was believed to be holding weapons.
Another U.S. official said he has seen satellite imagery of that attack that shows a hole in the center of a building's roof with the walls still largely intact.
That would strongly indicate a laser guided bomb was used with a fused warhead that exploded after the bomb entered the building roof. The photo is highly classified and not expected to be publicly released.
All of these events have sparked a flurry of controversy in intelligence services around the world about whether the Israelis bombed a secret Syrian nuclear program.
The Israeli government was very happy with the success of the operation, sources said after the airstrike earlier this month.
Syria accused Israel of a "flagrant violation" of its obligations after the attack. E-mail to a friend