One of the big targets was the country's aviation sector.

It triggered a global scramble by aircraft owners to get their planes out of the country

before the sanctions came into effect.

515 leased aircraft worth an estimated $10 billion were stuck in Russia.

Meanwhile, the businesses that rent out these aircraft were trying to work out how to recover

their assets and avert a crisis.

From a legal perspective, it's probably the most significant story in aviation.

Paul Jebely is chair and founder of the Hague Court of Arbitration for Aviation,

a specialized court to mediate disputes in the aviation industry.

It's been earth-shattering. I don't recall in 15 plus years of practice there ever being

a situation quite like this, both on magnitude and on scope. It's been very significant.

Accusations of theft by the Russian state came after the Kremlin signed a new law

on March 14th, two weeks after its invasion of Ukraine,

which allowed foreign jets to be re-registered in Russia.

This made it possible for the jets to fly domestically, but doing this without the sign-off

of the plane's original owners is illegal, and could trigger several long-term, costly

consequences in the process.

Six months after the crisis began, it was estimated lessors had been able to recover

around 80 aircraft, leaving more than 400 still stranded, with an approximate market

value of $8.5 billion.

It's the business of aircraft lessors to lease aircraft in jurisdictions across the

world and certainly before this, Russia was one of the riskier jurisdictions,

but exactly nobody expected something like this to happen.

More than half of the planes in our skies don't actually belong to the airline you're flying with.

They're owned by aircraft lessors.

Contracts can be short or long, include insurance and crew or not.

But leasing has risen in popularity over the years as a way for airlines to quickly scale up and down.

The situation in Russia has put the industry in the spotlight.

And it's the world's aircraft leasing capital that's the most exposed.

Irish aircraft leasing groups are among the worst affected,

with planes worth more than $4 billion leased to Russian airlines.

Ireland's journey to becoming an aircraft leasing powerhouse began in the 1970s when

Ryanair's future co-founder Tony Ryan set up Guinness Peat Aviation.

Business took off, with the company flouting a $4 billion valuation at its peak.

Shortly after, however, a failed stock market listing led to the company's downfall.

The company's assets were acquired by GE Capital, which was later acquired by AerCap,

now the biggest aircraft lessor in the world.

But Ireland's footprint is larger than just AerCap.

Fourteen out of the world's top 15 lessors are headquartered in the country.

Irish lessors manage more than $100 billion in assets and 60% of the world's leased aircraft.

This means an Irish-leased aircraft takes off every two seconds.

More recently, the Irish government has been incredibly sort of forward thinking in

terms of its double taxation treaties, which when you're leasing aircraft is very efficient

for withholding taxes.

Michael Graham values leased aircraft and has been analyzing the effect

of Russia's invasion on the leasing market.

He's also Irish.

Tax is often cited as the only reason that lessors are in Ireland. There are plenty of low tax jurisdictions.

But I think Ireland has that sort of extra depth of talent and a supportive government as well.

Ireland's corporate tax rate of 12.5%, one of the lowest in Europe, has successfully

attracted many of the globe's biggest multinational companies.

But it has agreed, along with 130 other countries, to operate a 15% minimum tax rate from 2023 onwards,

for companies earning more than €750 million globally.

Between 2009 and 2018, income for companies connected to the aircraft leasing business

rose by almost 235%.

Profits rose even more, a 327% increase, reaching €4.7 billion in 2018.

However, businesses paid just under €600 million in taxes that year and an average

of €223 million per year in that period.

As the size and volume of Irish leasing companies grew, so too did the airlines' reliance on leased aircraft.

Leasing planes is far less of a financial commitment than buying them.

It also allows airlines to operate newer planes and increase fleet capacity much faster.

In nearly five decades, the percentage of aircraft on commercial lease has soared from

0.5% to more than 50%.

Russia is the fourth largest source of Irish companies' leasing income after China, the U.S. and Ireland.

As a result, the sanctions on Russia are likely to cause a financial hit.

Why is Russia such a big market for Irish lessors and lessors in general?

Just it's a large market for domestic and international passenger travel and what that

means is that it's a large market for aircraft and many airlines do not own their aircraft outright.

So, it was very much natural that the Russian fleet was as sizeable as it was for the aircraft

leasing community.

It's had a very significant disruption for the aircraft lessors that have been impacted in particular,

but also it's caused shockwaves throughout the entire aircraft leasing and aircraft financing community as well.

While AerCap has the highest exposure to the Russian market, SMBC Aviation Capital has

a larger percentage of their fleet stuck in the country.

However, the impact on their bottom lines is expected to be minimal.

All the lessors declined to comment when CNBC reached out to them.

Can the authorities give special dispensation on grounds that this is an extraordinary circumstance?

The best way to think of commercial aircraft I always say is they are paper planes.

They are only as good as the documentation and maintenance records in particular.

Unfortunately, for the lessors who have recovered aircraft, many of them do not have a full suite of maintenance records.

For the safety regulators to allow planes back into commercial service,

lessors need to put each aircraft through long and expensive checks to reconstruct its records.

Some aircraft in recent years, they've tried to digitize them.

But the reality is, you still need the sort of grubby fingerprint, hard copies,

and you can rebuild maintenance records, but it is expensive, it takes time.

And don't forget, maintenance records obviously get longer over time, so the older the aircraft,

potentially the more expensive it can be to rebuild the maintenance record.

The fact is that when these aircraft are recovered, they will have far less value than they do

today and that revolves around the central question over whether these aircraft

are total losses, but I don't believe we're quite at that point yet for the majority of the fleet.

In the meantime, lessors affected by the sanctions have begun insurance claims;

AerCap's is worth $3.5 billion.

This will all result in a generation of litigation, and it will keep folks like me and all my

peers quite busy for the foreseeable future.

Is this terminal for the lessors or is this just a severe impact on their balance sheet?

I think it's probably the latter. I think it's important to put this crisis in the context

of what lessors have been through in the last two and a half years.

And what's been most pleasantly surprising is that lessors have come through this relatively strong.

So I don't think it's terminal for the leasing community, but it's a challenge they'll have to overcome.