Geoff Brumfiel

Updated on Monday at 12:40 p.m. ET

Iran has crossed another line set in the 2015 nuclear deal between it and major world powers.

According to state media, Iran has begun enriching uranium above levels enshrined in the agreement. The move sends a signal that Iran is losing patience with a deal that has not provided the economic relief promised, more than a year after the United States withdrew from the agreement.

Iran is on the verge of crossing a key line included in the nuclear deal it reached with the U.S. and other powers in 2015. As soon as Thursday, it's expected to announce that its uranium stockpiles have exceeded limits set by the deal.

Victoria Girgis was leading a public outreach session at the Lowell Observatory in Flagstaff, Ariz., when one of her guests noticed a string of lights moving high overhead.

"Occasionally, you'll see satellites, and they look kind of like shooting stars moving through the sky," Girgis says. "But this was a whole line of them all moving together."

In January, a group of high-level military commanders gathered at an air base in Yemen. It was far from the frontlines of the country's ongoing civil war.

Then, without warning, a small drone appeared out of the sky and exploded, spraying the group with shrapnel. According to news reports, the blast killed several, including the Yemeni government's head of military intelligence.

North Korea's newest missile has a striking resemblance to an advanced Russian design, according to experts analyzing images from a test of the weapon on Saturday morning.

The missile, which North Korea describes as a "tactical guided weapon," appears superficially to be nearly identical to Russia's Iskander missile — a highly accurate short-range weapon capable of striking targets more than 150 miles away.

On the outskirts of Riyadh, Saudi Arabia is building what it sees as the future of its energy production.

Updated at 5:30 p.m. ET

A secretive group of scientists who advise the U.S. government on everything from spy satellites to nuclear weapons is scrambling to find a sponsor after the Defense Department abruptly ended its contract late last month.

The group, known as the Jasons, will run out of money at the end of April. The Pentagon says that the group's advice is no longer needed, but independent experts say it has never been more relevant and worry the department is throwing away a valuable resource.

Earlier this year, President Trump laid out an ambitious plan for U.S. missile defenses. "Our goal is simple," Trump said during a speech in January. "To ensure that we can detect and destroy any missile launched against the United States, anywhere, anytime, anyplace."

To reach that goal, the administration's proposed new defense budget calls for hundreds of millions of dollars to study the use of lasers and particle beams in space. "It's new technology," the president said.

Except it isn't.

Early Friday morning, Japan's Hayabusa2 spacecraft detonated an explosive device over a small asteroid. The goal was to create a fresh crater that will later be studied by the spacecraft.

India says it shot down one of its own satellites, making it only the fourth country to test an anti-satellite weapon.

India's Prime Minister Narendra Modi announced the successful test on Wednesday in a rare national address and on social media. The test would "have a historic impact on generations to come," Modi said in a tweet.

The announcement comes just weeks before national elections in which Modi's party has tried to paint itself as being hawkish on national security.

Updated at 7:45 p.m. ET

A Spanish court says assailants who broke into North Korea's Embassy in Madrid last month later fled to the U.S.

According to new documents unsealed on Tuesday, the perpetrators of the attack included a U.S. citizen and another resident. The leader of the plot fled via Lisbon to Newark, N.J., and offered stolen material to the FBI in New York.

The Missile Defense Agency says it has conducted another successful test of its ground-based interceptor system.

Monday's test involved a missile carrying a dummy warhead fired from Kwajalein Atoll in the Pacific Ocean toward the U.S. West Coast. Sensors tracked the missile as it flew, and then two interceptors were launched from Vandenberg Air Force Base in California.

Updated at 5:40 p.m. ET

Satellite imagery of a space launch center in northern Iran suggests a second attempt to launch a satellite has failed.

The imagery, taken Wednesday by San Francisco-based company Planet and shared with NPR, shows burn scars on a newly painted launchpad at the Imam Khomeini Space Center. The burns appeared after days of activity at the site, which suggested Iran had been preparing for a launch.

At a Russian base on the Baltic Sea, construction is underway to house a new generation of nuclear-capable missiles.

Tentlike structures have popped up to shelter the mobile missile system, known as Iskander, which is capable of firing weapons with both conventional and nuclear warheads. Recent satellite imagery of the territory, known as Kaliningrad, also shows that old buildings on the base are being demolished.

The U.S. Department of Energy has started making a new, low-yield nuclear weapon designed to counter Russia.

The National Nuclear Security Administration says production of the weapon, known as the W76-2, has begun at its Pantex Plant in the Texas Panhandle. The fact that the weapon was under production was first shared in an e-mail to the Exchange Monitor, an industry trade magazine, and independently confirmed by NPR.

Big, important scientific breakthroughs are built of small, incremental experiments. And the partial government shutdown is already interfering with some of that research.

Scientists often depend on the government for grant funding, expertise and — in some cases — even regulatory approval. With the shutdown, some researchers are missing those key elements of scientific collaboration. Here's how some scientists say the shutdown is affecting their work.

Carbon dioxide emissions in the U.S. are on the rise again after several years of decline, and a booming economy is the cause.

That's according to a report out today from the Rhodium Group, an independent research firm that tracks CO2 emissions in the U.S.

Updated at 8:35 p.m. ET

Shoot it down. Jam it. Use a missile or maybe a net.

There's no shortage of ideas about how to stop a drone, but as the past few days at London's Gatwick Airport show, the reality is far more difficult.

From Wednesday night to Friday morning, flights in and out of Gatwick were halted after a small drone, or perhaps multiple drones, were spotted over the airfield. Hundreds of flights were canceled and thousands of passengers saw their holiday travel plans grounded.

For years, the world has imposed strict sanctions on North Korea in an attempt to stop its development of nuclear weapons. Officials from nations across the globe have seized shipments of raw materials, shut down shell companies and interdicted ships smuggling equipment.

But despite these efforts, last year North Korea tested the most powerful weapons known to humanity: a nuclear device far larger than any it had tested before, and an intercontinental ballistic missile that put much of the world, including the U.S., within range.

Updated Dec. 12 at 4:20 p.m. ET

North Korea appears to be expanding a missile base in a remote, mountainous part of the country, according to new commercial satellite imagery studied by independent researchers.