Riddle me this: Syrian dictator Bashar al-Assad, who’s broke, buys chemical weapons from North Korea’s Kim Jong Un, who needs the cash. So who foots the bill?

Follow the money and the answer will likely take you to the country that backs the Syrian strongman, has ties with the Nork tyrant — and is marching on with a grand plan to dominate the Mideast: Iran.

A confidential report, prepared by a panel of experts and scheduled to circulate Friday among members of the UN Security Council, details two recent incidents in which unidentified countries intercepted shipments of chemical armaments from North Korea to Syria.

Chemical weapons, remember, were at the heart of President Barack Obama’s unenforced Syrian “red line.” President Trump recently was so horrified by their use that he ordered a Tomahawk missile attack on Syrian targets.

The UN panel, as first reported by Reuters, doesn’t say when or where the chemical shipments were intercepted. The experts, monitoring North Korea’s sanctions, also didn’t specify who financed the deal.

But we can make an educated guess.

“It’s plausible that Assad’s largest financial and military backer would have paid for the shipments,” says Mark Dubowitz, CEO of the Foundation for Defense of Democracies.

After all, Iran supplies cash-strapped Assad with free oil, food, ammunition and pretty much anything else he needs to maintain a grip on power after more than six years of ferocious civil war. Members of the Islamic Revolutionary Guard Corps fight in Syria on his behalf, alongside Hezbollah and other Iranian proxy militias.

And remember that nascent Syrian nuclear facility Israel destroyed in 2007? North Korea helped design and build it. Israeli intel sources say Iran paid Pyongyang up to $1 billion to finance the project.

With easier access to funds than they had before the nuclear deal Iran cut with Obama, the mullahs are toiling to realize their dream of restoring past Persian-empire glory.

Syria is an important part of it. So is Hezbollah-dominated Lebanon.

The mullahs have a problem, though: Last week, the outgoing commander of the Israeli Air Force, Amir Eshel, publicly acknowledged for the first time that his jets have conducted at least 100 sorties over Syria, bombing weapons deliveries from Iran to Hezbollah.

So what does a country intent on arming its allies and proxies to the teeth do when deliveries are so rudely interrupted?

Iran reportedly decided to build a missile factory in northern Syria with plans to launch two arms factories in Lebanon. Can the areas of Yemen controlled by Tehran-backed Houthi rebels be far behind?

Creating indigenous arms plants for Iran’s far-flung allies would be an “alarming escalation, and I think countries like the US should be concerned,” Abdullah bin Abdulaziz al Rabia, a special adviser to Saudi King Salman, told me this week.

The entire region is concerned. Top Israeli intelligence officials met with Trump’s National Security Adviser H.R. McMaster this week in Washington to devise a strategy that would ensure Iran and Hezbollah don’t dominate post-war Syria.

The idea is to stop the mullahs’ expansionism without an all-out war. This week, UN Ambassador Nikki Haley said a UN force charged with disarming Hezbollah, UNIFIL, “isn’t pursuing its mission aggressively.” She warned the situation in Lebanon is, therefore, “much more dangerous.”

But the hapless United Nations won’t disarm Hezbollah, now the dominant political, military and social power in Lebanon. The world’s favorite activity — ignoring the obvious — has worked for Iran in Lebanon, and it now plans to Hezbollah-ize other parts of the region.

And as long as the mullahs feel they can pursue expansionist policies with impunity, they’ll pal with the world’s worst to sow the seeds of war.

Pointing to Iran’s alliance with Kim and Assad, Israeli Defense Minister Avigdor Lieberman recently told the Israeli news service Walla that North Korea, Iran, Syria and Hezbollah make up an “axis of evil.”

Turns out Dubya’s old phrase, which has come in for years of criticism and scorn, is useful after all. Maybe it’s time to revive it.