From Iran to Ukraine, this is the era of cheap drone warfare.

Kiev endured an aerial assault by Russian drones.

The Kremlin seeing the biggest drone attack yet inside Russia.

Missiles, drones, a barrage of attacks in the Red Sea.

Iran has started a direct attack on Israel by launching dozens of drones.

Drones have changed the landscape of war.

It's like the AK-47 of 21st century warfare.

They're a feature of the modern battlefield, mostly because they're so inexpensive and easy to make.

And many of these drones can be traced back to Iran, a country under strict international sanctions.

So how are drones changing the economics of warfare?

This attack was a direct response to something that happened on the 1st of April when Israel bombed a building close to the Iranian embassy in Damascus.

There were some very senior Iranian generals in that building who died in that attack.

The Iranians had to respond.

These were designed to overwhelm Israeli defenses while a separate battery of missiles were following at a distance.

So if everything had gone to plan, the missiles would have been able to penetrate those defenses.

We've never seen a swarm this big.

Scores all set off at the same time.

And it could be a game changer in the way war is conducted.

Asymmetry is often what decides a conflict.

It's effectively when one side is more powerful than the other.

Historically, at least in the modern history of warfare, every technological advance has come from the technologically superior military power.

So the most powerful countries got more powerful and the gap between them and the rest widened.

To address this kind of mismatch, the weaker power seeks a way to catch up.

An asymmetrical tool.

Drone warfare is a way to close the capability gap and it's a way to diffuse power.

Drones come in a full spectrum.

Most of the drones that we're using in the West, like the Reaper drone, which has been somewhat the iconic drone that we've used since 9-11, which cost in the region of $30 million.

At the other end of the spectrum are the drones we saw over the weekend.

They are what are called kamikaze drones.

All they do is carry a payload of explosives and they ram into a target and blow up.

In military circles, they're called lawnmowers on wings.

People are saying that the Shahi drone is Iran's AK-47 because it is extremely versatile and can be produced in high quantity at low cost.

Now we entered into the next phase of drone warfare, which is low-tech drones at large quantities.

The main Iranian drone company is called Shahed Aviation Industries, which the U.S. says is a subsidiary of the Revolutionary Guards.

They have been using scores and scores of small companies to circumvent sanctions.

They have their own smuggling networks globally where they can get their hands on any sort of component part that they need.

Shahed drones can be found in Syria, Russia, Ethiopia, Tajikistan and Venezuela.

The Shahed-136 is the best known.

It carries up to 50 kilograms of explosives and has a range of up to 2,500 kilometers, which lets Iran strike targets within Israel without needing to use proxy forces in Lebanon,

Gaza and elsewhere.

This is where the economic consideration comes in.

They cost anywhere between $20,000 and $50,000.

Others are even cheaper, as little as $1,000.

Each missile the Israelis were using cost in the region of hundreds of thousands of dollars, if not millions of dollars.

America and Israel together probably spent around $1.5 billion in defending against the

Shahed drones, while the Shahed drones all put together probably cost the Iranians in the region of something like $3 million.

You can drain your enemies' military budgets by them having to restock their air defences at a very high cost.

If Iran didn't have these drones and these missiles, it would have to send jet fighters over long distances in order to attack Israel.

If Israel shot down those jet fighters, that would be a huge blow for Iran.

Iran's proxy in Yemen, the Houthis, have already managed to clog up trade in the Red

Sea with the threat of drones and inexpensive but accurate missiles.

Drones have changed the war in Ukraine too.

Cheap, consumer, mainly Chinese, models have been adapted to drop explosives on multimillion-dollar tanks.

And more sophisticated drones have been used to great effect against the Russian Navy.

Those drones have been key in Ukraine's ability to destroy quite a large part of Russia's naval fleet in the Black Sea.

The U.S. military has leaned increasingly on fewer but more sophisticated and more expensive weapons systems.

All of this is provoking big rethinks about how to kit out modern armies.

Over time, we need to find a better way to defend against these drones at lower cost.

We know that the U.S. has been developing weapons to counter the threat of drones.

Lasers, the use of anti-aircraft weapons, the German anti-aircraft weapons have been very effective in Ukraine, for instance.

But there's a big economic challenge here too.

For the defense industry, it's more profitable to rely on the multibillion-dollar research and development of sophisticated platforms where you only sell one or two or three of.

In other words, big defense companies don't consider cheap drones an attractive business proposition.

To change that thinking, governments would need to provide defense companies with the motivation to build the tech.

I think what is needed is an incentive and a push to say we need more platforms at cheaper cost and use them in a networked way.

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