There's no clear link between a massive explosion at an Iranian ballistic missile base, a report by the U.N. nuclear watchdog accusing Tehran of working on nuclear weapons and the mysterious death of a former Revolutionary Guard chief's son in Dubai.

But taken together, along with other recent events, they add up to a sharp rise in tensions in the Persian Gulf with U.S. forces weeks away from wrapping up their withdrawal from Iraq.

The United States and Israel have been waging a covert war of sabotage, assassination and cyber weapons against Iran for several years to disable Tehran's nuclear program.

As U.S. conventional military power in the region wanes, it would make sense for clandestine operations to intensify, just as Israel seems to be stepping up the heat with threats of pre-emptive strikes.

The United States "is leaving behind a power vacuum" in Iraq "that Iran has been patiently waiting to fill" since 2003, observed analyst Reva Bhalla of the Texas-based global intelligence consultancy Stratfor.

"Iran intends to exploit this opportunity to not only consolidate its position in Iraq, but intimidate its Arab neighbors into accommodating Iran on a number of strategic issues."

One of its prime weapons is its Shehab-3 ballistic missiles, numbering as many as 200, controlled by the elite IRGC.

In the wake of recent U.S. threats to eliminate commanders of the Islamic Revolutionary Guard Corps, Iranians -- and others in the region -- view Saturday's explosion at the Aghadir missile base 25 miles southwest of Tehran as proof of U.S. complicity.

The blast, which Tehran claimed was accidental, killed Maj. Gen. Hassan Moghaddam, acknowledged as the architect of Iran's strategic missiles forces.

If the Americans were behind the explosion, that would mark a dramatic and dangerous escalation in the shadow war that has been escalating over Iran's nuclear program since 2007.

It was not clear why Moghaddam, reportedly trained in ballistic science by China and North Korea, was at the Alghadir base.

But if the explosion was the result of sabotage and the general was targeted, it's a provocation the Iranians cannot ignore.

Already, three nuclear scientists have been assassinated in Tehran since 2007. Iran blamed Israel's Mossad intelligence service.

Mossad and U.S. intelligence have for years been running dummy companies in Europe through which they've funneled nuclear equipment, deliberately made defective, to Iran to sabotage the nuclear project.

These stratagems have slowed down the program, but as the Nov. 8 report by the International Atomic Energy Agency observed, it has not stopped.

The report failed to provide unambiguous proof that Iran is striving for nuclear arms. But it bolstered the arguments of those, like the United States and Israel, who say that's what Tehran is doing.

The report cited "serious concerns regarding possible military dimensions to Iran's nuclear program," information the agency found "to be, overall, credible … that Iran has carried out activities relevant to the development of a nuclear explosive device."

This has given impetus to Western diplomatic efforts to tighten U.N. sanctions imposed in 2010, but these are likely to be stymied by China and Russia.

That leaves covert force and, from Israel at least, military action against Iran's nuclear infrastructure.

Britain's Guardian newspaper Monday quoted a former director of an Iranian state-run organization as saying the Alghadir explosion was "part of a covert war against Iran, led by Israel."

There was a similar explosion at an IRGC missile base near the city of Khorramabad in western Lorestan province Oct. 12, 2010. Like Alghadir, the Khorramabad installation also housed Shehjab-3 missiles, which can reach Israel.

In October, the U.S. administration unveiled an alleged Iranian plot to assassinate the Saudi ambassador in Washington.

The claim was widely disparaged, but it fueled the clamor for tough action against Tehran.

Then, on Sunday, Iran's media reported that Ahmad Rezai, son of former IRGC commander Mohsen Rezai who's now secretary of Iran's Expediency Council, had been found dead in a Dubai hotel.

Some reports listed it as suicide. But a senior official in Tehran said the death was suspicious and involved electric shocks.

Who would want to kill Rezai remains unclear. But analyst Kaveh Afrasiabi observed that "there's no shortage of analysis in Iran that connects these seemingly disparate incidents as parts of a systematic effort to destabilize Iran."