Saudi Arabia, the United Arab Emirates and Bahrain have all recently accused Tehran of either arming or seeking to arm Shiite militants in those countries.
Several clandestine arms shipments apparently destined for Hezbollah in Lebanon and Hamas in the Palestinian-ruled Gaza Strip have been intercepted by Israel and Turkey in the eastern Mediterranean and the Red Sea.
The Israeli daily Haaretz reported that Tehran has used the preoccupation of the region and the West with the political shock waves jolting the Arab world since January to boost its gunrunning operations.
It quoted intelligence sources as saying that "only a relatively small quantity of smuggled weapons is being intercepted.
This include the Israeli navy's seizure of several tons of Iranian arms aboard the German-owned freighter Victoria, registered in Liberia, in international waters 200 miles off the Israeli coast.
The ship had sailed from the port of Latakia in Syria, Iran's key Arab ally, and was en route to Alexandria, Egypt, when it was boarded. The Israelis say the arms were to be smuggled from Egypt through underground tunnels to Hamas in Gaza.
Soon after that interception, the latest in a long line of such seizures by Israel in recent years, Turkey announced that it had stopped two Iranian cargo planes that were found to be hauling mortars and others arms to Syria. These, say intelligence officials, would be passed on to Hezbollah or Hamas.
The intercepts took place on what the Israelis call the northern route from Iran, via Syria, which borders Lebanon. But Iran also runs a southern smuggling corridor from the gulf port of Bandar Abbas, a major Revolutionary Guards base, through Eritrea and Sudan on the Red Sea.
Most of the arms shipped on that route are for Hamas in Gaza. Before Egypt's long-ruling president, Hosni Mubarak, was toppled in a pro-democracy uprising Feb. 11, his regime had sought to curb the gunrunning.
But now that he's gone, the Israelis fear that the military council currently running Egypt, or a successor regime possibly dominated by Islamists, will be more willing to aid Hamas against Israel.
Sudan's government claimed April 5 that Israel was behind the assassination of two men killed when their car was mysteriously blown up outside Khartoum. Arab media reports identified one of the men as a senior member of Hamas' military wing who was involved in a gunrunning operation through Sudan.
The increase in covert Iranian activity is more noticeable in the Persian Gulf, where longtime rivals Iran and Saudi Arabia are locked in an intensifying cold war for domination of the oil-rich region.
Saudi military intervention in Bahrain, an island kingdom linked to Saudi Arabia by a 16-mile causeway, on March 14 to aid the 200-year-old Al-Khalifa dynasty aggravated this rivalry.
The Khalifas were struggling to crush by force an opposition movement by Bahrain's Shiite majority demanding the ouster of the Sunni monarchy.
Iran has long laid claim to Bahrain, headquarters of the U.S. Navy 5th Fleet, the main component of the U.S. military presence in the Persian Gulf.
Tehran has clearly intensified its covert activities in the gulf and the Levant amid the upheaval in the Arab world that has already brought down the leaders of two longtime U.S. allies, Egypt and Tunisia.
The U.S. military withdrawal from Iraq, long a buffer against Iranian expansionism until the Americans invaded and toppled Saddam Hussein, gave Iran its opening to expand its influence.
"As Iran has reminded every U.S. ally in the region amid the recent unrest, from Bahrain to Saudi Arabia and from Yemen to Israel, Tehran is the rising power and the one filling the vacuum as the Americans leave," observed the global security consultancy Stratfor.
"While it is difficult to fully or accurately assess the extent and limitations of Iran's overt and covert capabilities … geopolitics suggest that Iran, in deliberately sending a signal the region, has not yet activated all of its tools nor exerted maximum effort -- indeed, this the heart of the Iranian threat: there is more to come."