Hello, everyone, I'm Carl Azuz.

Late last week, an Iranian nuclear scientist was assassinated.

His name was Mohsen Fakhrizadeh.

He was said to have been involved for decades and Iran's controversial nuclear program.

We don't know exactly how he was killed.

Different Iranian news agencies have had differing accounts of what happened, but Iranian officials say the attack was complex and involved weapons that were controlled remotely.

And Iranian media say it involved gunfire and an explosion from a car that was located near the one Fakhrizadeh was traveling in east of his country's capital.

CNN cannot independently confirm this information, and while other countries say they don't know who carried out the attack, Iran is blaming Israel.

These two nations are enemies in the region.

A news agency run by the Iranian government says the weapons that were used were made in Israel and had Israeli markings on them.

But the agency didn't show any pictures to support its accusation, and again, CNN can't confirm that report.

Israel's government hasn't commented on Iran's accusation, but Israel's prime minister did mention the scientist's name in 2018, saying Fakhrizadeh was the leader of a secret nuclear weapons program, and other officials have said that as well.

More recently, an Israeli settlement affairs minister says he has no idea who killed Fakhrizadeh, and he called the attack quote "very embarrassing for Iran."

The leaders of several countries have spoken out against the attack, and they've called for calm in the region.

But Iranian leaders say the assassination was an act of state terror, and they promised that they will take revenge for it in the days ahead.

Part of the reason why international officials are concerned about that.

The United States is a close ally of Israel and a rival of Iran.

So the question is, if Iran strikes Israel, will the US get involved?

Moving northwest to Europe now.

Most countries there are under some sort of locked down, either complete or partial because of coronavirus.

And they're grappling with decisions of what restrictions they should lift and when they should lift them as Christmas approaches and people want to ski, shop, go to restaurants and celebrate with their families.

This is what Christmas normally looks like, but this year, something's missing.

London's dazzling Christmas lights have been switched on, but the coronavirus has prevented the usual fanfare, and the shoppers are not out in force, although nonessential stores are set to reopen on Wednesday when the UK exits a second national lockdown.

'Tis the season to be jolly, but it is also the season to be jolly careful.

Across Europe, gatherings for traditional church services will be smaller due to the pandemic.

Here at St. Paul's, it's going to feel very different this year.

Normally, we can get 2,000 people into this great space.

But this year we can only get 250 people at a time, so it's going to feel much smaller.

But what we can do is livestream.

In Germany, most of the traditional Christmas markets where tourists flock to glug Glühwein and eat Bratwurst will be closed.

But for those who can't do without some festive cheer, there's an innovation forced by the pandemic, the drive-thru.

In Italy, the former European epicenter of the virus, the prime minister is urging people to avoid another tradition: holidays on the slopes.

Meanwhile, Switzerland is allowing skiing with precautions.

There's no big difference.

I think we're very lucky that we could go skiing once you're used to the mask it's okay.

Here in France, Emmanuel Macron has said that people will be allowed to travel across the country to be with their families for Christmas from December 15th , if the daily number of cases reaches a level of about 5000.

European leaders, though, are urging caution when it comes to travel.

The World Health Organization said last week that Europe still accounted for half of all new COVID-19 cases and new deaths globally.

We must learn from the summer and not repeat the same mistakes.

Relaxing too fast and too much is a risk for (a) third wave after Christmas.

Either way, this will be a Christmas like no other.

With hundreds of thousands of lives lost across Europe, celebrations will be scarred by the loss of life and the reality that the COVID pandemic remains far from over.

Melissa Bell, CNN, Paris.

10-second trivia!

What was the first airline in the world?

Delag, Qantas, KLM, or Pan Am?

KLM is the oldest airline that still operating, but Delag was the first airline ever--it carried paying passengers on Zeppelins.

Those planning to fly in the year ahead may see some major differences on airlines, and it doesn't stop at just wearing a mask.

Qantas, a carrier based in Australia, says international travelers aboard its planes will be required to have had a coronavirus vaccine when one becomes available, and the head of Qantas says he expects other airlines to do this, too.

The industry has been hit hard by the pandemic, with many travelers afraid of catching COVID on planes.

But the vaccine requirement may also hurt the airline business if a lot of people refuse to get the shot, as U.S. polls have indicated they would.

Right now, some international passengers on other flights are required to take a rapid COVID test before they can get on the planes.

Though the rapid test is faster and cheaper than the other kinds, it's not as effective at detecting coronavirus and some doctors are concerned that people who are sick could still test negative and get on planes.

But this is another step being taken in a landscape that's dramatically changing in response to a disease.

I have to say it is unusual experience being on a plane where, you know every passenger has had a COVID test.

[CNN's Richard Quest went on board United Airlines first rapid-test COVID flight]

Airport COVID testing--the new passport to travel!

You have to think of this not about what's happening now with one flight to London.

But imagine that this is the way it's going to be for multiple flights across the ocean, as testing becomes more accepted by various governments.

Then you're gonna have 5, 10...

Who knows how many flights with passengers doing the COVID test?

Now that was a piece of cake!

So what if, as it will happen, somebody tests positive?

If someone tests positive, they'll be removed from this area and taken to a private location where the CDC will be contacted and we'll notify the appropriate health organizations to help support that customer.

We'll take steps so that they're not... they won't fly that day, obviously, for their safety and the safety of everyone else on the flight.

And so for the flight that guarantees everybody is COVID-negative.

Before takeoff, we're told the plane has been sanitized, everything's being made clean and there are wipes on every seat, a couple of them were told that there are extra masks available if you need them.

The transatlantic flight from New York to London is one of the busiest routes in the world.

This flight , which has a capacity of over 270, carries just 36 passengers (12.59%).

So, we are on our way to London.

And I have since learned that one of the passengers who was meant to be on board did test positive for coronavirus.

United already had a plan in place.

The person being isolated and being taken care of, meaning the rest of the flight to proceed with greater confidence and security.

United and the rest of the industry thinks this is the way forward.

The penguins recently showed up at Soldier Field in Chicago.

And before you say, I've got my sports leagues confused.

Told you, penguins.

Of course, Soldier Field has hosted greats like Butkus, Ditka and Peyton.

Recently, it was visited by Charlotte, Izzy and Tambo.

They usually play at Chicago's Shedd Aquarium, but it's closed right now, so workers have been taking the Penguins on "field trips".

It's not the first time we've heard about penguins and football.

Consider the great Ray Flipper-ty.

There's Krill Carter, George wrapping, John Waddell, Derrick Bird-rookery.

A lot of players fit the Bill Parcells, and not all of them are dolphins, so you just never know whom you're gonna find in the huddle.

We found Maynor High School in the huddle of comments on our YouTube channel.

It's located in Maynor, Texas, and it is the main-er focus of today's shoutout.

I'm Carl Azuz.