Patriot missiles are seen at the Rzeszow-Jasionka Airport on March 25, 2022, in Poland.

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CNN  — 

Russia’s attacks on Ukraine’s power grid are targeting the entire population, casting people into darkness and cold, and pushing the US closer to sending the Patriot missile defense system long sought by Ukraine’s government.

But news, first reported by CNN, that the US is finalizing plans to send the system to Ukraine triggered a cryptic warning from Russia’s US embassy Wednesday of “unpredictable consequences.”

Sending the Patriot missiles would be seen as an escalation by the US, Russian Foreign Ministry spokesperson Maria Zakharova added Thursday.

“Earlier, many experts, including those overseas, questioned the rationality of such a step which would lead to an escalation of the conflict and increase the risk of directly dragging the US army into combat,” Zakharova said at a briefing in Moscow.

The Patriot system is expensive and complicated and requires intensive training for the multiple people it takes to operate it, but could help the country guard against Russian attacks that have left millions without power.

RELATED: Ukraine keeps patching up its power grid. But Russia’s barrage could force more Ukrainians to flee as winter bites

Asked Thursday about Russian warnings that the Patriot system would be “provocative,” Pentagon press secretary Brig. Gen. Pat Ryder said those comments would not influence US aid to Ukraine.

“I find it ironic and very telling that officials from a country that brutally attacked its neighbor in an illegal and unprovoked invasion … that they would choose to use words like provocative to describe defensive systems that are meant to save lives and protect civilians,” Ryder told reporters.

“Despite Russia’s propaganda to portray themselves as victims, it’s important to remember that Russia is the aggressor here,” he said.

However, he added, “The US is not at war with Russia, and we do not seek conflict. Our focus is on providing Ukraine with the security assistance it needs to defend itself.”

Ryder also said the US would amp up its training of Ukrainian armed forces with exercises in Europe.

Russia’s growing nuclear rhetoric

Frustrated on the battlefield and short of ammunition, Russian officials have seemed to embrace nuclear rhetoric in recent weeks.

In what may be a no less subtle message than calling the Patriot deployments provocative, Russia’s defense ministry shared video of the installation of a “Yars” intercontinental ballistic missile into a silo launcher in the Kaluga region for what Alexei Sokolov, commander of the Kozelsky missile formation, called “combat duty as planned.”

Russian President Vladimir Putin recently said the threat of nuclear war was growing and suggested his country could abandon its “no first use” nuclear weapons doctrine, under which Russia has said it would only use nuclear weapons to defend its homeland. Putin’s comments came after drone strikes hit military infrastructure deep inside Russia. Russia’s military blamed Ukraine for the strikes.

Appearing this week on Russian state TV, Commander Alexander Khodakovsky of the Russian militia in the Donetsk region suggested Russia could not defeat the NATO alliance in a conventional war.

“But we have nuclear weapons for that,” Khodakovsky said, according to CNN’s translation.

What to know about the Patriot defense system

The Patriot system is a conventional long-range defense system the US has provided to multiple allies around the world.

It requires a relatively large number of personnel to be trained, according to CNN’s Barbara Starr and Oren Liebermann, who were first to report the US is close to sending the system to Ukraine.

From Starr and Liebermann’s report:

Unlike smaller air defense systems, Patriot missile batteries need much larger crews, requiring dozens of personnel to properly operate them. The training for Patriot missile batteries normally takes multiple months, a process the United States will now carry out under the pressure of near-daily aerial attacks from Russia.

The system is widely considered one of the most capable long-range weapons to defend airspace against incoming ballistic and cruise missiles as well as some aircraft. Because of its long-range and high-altitude capability, it can potentially shoot down Russian missiles and aircraft far from their intended targets inside Ukraine.

Half of Ukraine’s power infrastructure destroyed

Ukrainian President Volodymyr Zelensky has long sought more long-range missile systems from Washington and NATO allies. In a conversation with US President Joe Biden last Sunday, Zelensky thanked the US for its continued support and asked for more air defense help. He told Biden that “Russian missile terror” has destroyed about half of Ukraine’s energy infrastructure.

In an interview with The Economist published Thursday, Zelensky also rejected the idea recently suggested by US Secretary of State Antony Blinken that Ukraine seek to reclaim only land seized by Russia since February 2022 and not areas like Donbas and Crimea, which have been under Russian control since 2014.

“This would not be a finale,” Zelensky said.

Aiding Ukraine without getting directly involved

NATO Secretary General Jens Stoltenberg told the French news outlet France 24 this week, before the Patriot missile development, that the alliance still has two main objectives: provide aid to Ukraine and also make sure that NATO forces don’t become directly involved and escalate the war.

“We don’t have NATO troops on the ground. We don’t have NATO planes in the air over Ukraine. But we are supporting Ukraine in their right to defend themselves,” he said.

He said that despite Russia’s threats about nuclear weapons, there has been no detected change in Russia’s nuclear posture, but Putin’s rhetoric “is by itself reckless and dangerous.”

Some other notable Russia and Ukraine storylines

Old ammo. CNN’s Ellie Kaufman and Liebermann reported earlier this week on a US military official who says Russian forces have had to resort to 40-year-old artillery ammunition as their supplies of new ammo are “rapidly dwindling.”

“You load the ammunition and you cross your fingers and hope it’s gonna fire or when it lands that it’s gonna explode,” said the official, speaking to reporters.

The effect of months of military aid. It’s a completely different scale, but CNN reported last month the US is running low on some weapons systems and munitions it provides to Ukraine. Look for that storyline to become part of the US aid debate after Republicans take control of the House of Representatives next month and promise more scrutiny of US aid for Ukraine.

In the trenches. CNN’s Will Ripley filed a video report from trenches and fortifications being built along Ukraine’s border with Belarus, where there is growing concern about Russia once again assembling troops. Ripley talks to a sewing machine repairman turned tank driver.

Striking Donetsk. Ukraine has launched a serious attack in the Donetsk region, the area controlled by Russian-backed separatists since 2014, according to a Russian-installed mayor there.

Get more of CNN’s Ukraine coverage.