Russia is deploying long-range, precision cruise missiles to the western Atlantic that American defense officials say will allow Moscow to target Washington and other East Coast cities with conventional or nuclear attacks.

Moscow is adding Kalibr land attack cruise missiles to both warships and missile submarines that Moscow plans to use in Atlantic patrols near the United States, sorties that were once routine during the Cold War.

The new sea-based Kalibr deployments are expected in the coming months, according to officials familiar with intelligence reports of the Russian maritime operations.

The land-attack version of the Kalibr, known as the SS-N-30A by NATO, is a relatively new weapon and was showcased for the first time by Moscow in attacks on Syria that began in 2015

Russia has stated that over 100 Kalibr missile strikes were carried out against Islamic terrorists and other anti-Syrian government rebels.

The Office of Naval Intelligence in 2015 said the Kalibr is deployed on Russia's new Sverodvinsk-class nuclear attack submarine as well as older submarines and surface warships. A total of 32 Kalibrs can be launched from missile tubes on the new submarine.

Nuclear-armed Kalibrs will be deployed on Russia's new Borei-class missile submarines as well as the attack submarines.

Most of Russia's surface warships and many coastal vessels are being outfitted with the long-range missile.

The missile is considered very lethal because it flies close to the sea surface, frustrating efforts to detect and strike the missile with anti-missile systems.

"Russia plans to deploy Kalibr capability on all new design construction of nuclear and non-nuclear submarines, corvettes, frigates, and larger surface ships," the ONI said in a report, noting the missile gives even modest vessels "significant offensive capability."

"The proliferation of this capability within the new Russian Navy is profoundly changing its ability to deter, threaten or destroy adversary targets."

The missile also comes in anti-ship and anti-submarine variants.

According to ONI, the Kalibr land attack missile has a range of between 930 miles and 1,550 miles.

That range means a ship or submarine armed with Kalibrs and located 1,000 miles off the U.S. coast could target all American cities stretching from Boston to Miami and as far west as Chicago.

Kalibr is a concern for U.S. military commanders in Europe as a result of their deployment on ships and submarines in the Mediterranean and areas near Europe. The missile has been compared to the Navy's Tomahawk cruise missile.

Gen. Curtis Scaparrotti, NATO commander and commander of the European Command, told Congress last spring he is concerned about the submarine-launched Kalibr.

"The activity level of their maritime forces is up in Europe," Scaparrotti told the House Armed Services Committee, adding that the deployments were not normal.

"Most of their ships now have a Kalibr system on them," he said. "It is both conventional and can be nuclear, if they choose to do so. It's a very good system. It provides reach and precision, and, of course, wherever they have a ship, whether it's undersea or on the surface, many of their ships now have the Kalibr system on them."

Scaparrotti said the Russians are making "rapid progress" in developing the new Severodvinsk nuclear attack submarine, more capable Kilo submarines, and Kalibr cruise missiles.

Vice Adm. James Foggo III, commander of U.S. Naval Forces Europe, described the Kalibr as a missile "I'm very interested in."

"It's a capable weapon system and from where the Russians operate it's capable of targeting any capital in Europe," he said. "Do I think they'll do that? No, I don't, because I think that the NATO Alliance operates from a position of strength."

Foggo said it's important for the United States to know the location of Russian submarines in the European theater at all times.

Asked during a Pentagon briefing if all Russian submarines can be detected where they sail, Foggo said: "Well, I prefer not to comment on the tactical details and the operational issues. But I can tell you that we hold an acoustic advantage, and we will continue to do that. Our boats are the best in the world."

He also warned last year about the growing threat of Russian undersea warfare capabilities.

"Russia has renewed its capabilities in the North Atlantic and the Arctic in places not seen since the Cold War. For example, Russian forces have recently reoccupied seven for their former Soviet Union bases in the Arctic Circle," Foggo said.

"The improved capability of Russia to be able to project power into this [European] region and these strategic routes from the Arctic into the North Atlantic and the [Greenland, Iceland, United Kingdom] Gap is something that we need to pay particular attention to."

Russian submarines, Foggo said, "today are perhaps some of the most silent and lethal in the world, with the exception of our own."

Kalibr missiles deployed on a variety of launch platforms have "shown the ability to reach pretty much all the capitals in Europe from any of the bodies of water that surround Europe."

"We know that Russian submarines are in the Atlantic, testing our defenses, confirming our command of the seas and preparing a very complex underwater battlespace to try to give them an edge in any future conflict," Foggo said Oct. 4 in a podcast. "And we need to deny them that edge."

A Navy spokesman had no comment and a spokesman for the Northern Command, which in charge of defending the U.S. homeland, also declined to comment.

Mark Schneider, a former Pentagon nuclear analyst, said the Russians have stated that the Kalibr will be a major weapons system for the Russian navy and will be dual-capable—armed with both conventional and nuclear warheads.

"The Russians say the long-range version of the Kalibr is a nuclear capable missile with a range of 2,000 or 2,500 kilometers [1,242 miles or 1,553 miles]," Schneider said.

Russian state-run media reports have identified the new Severodvinsk-class submarine with Kalibr missile as part of the strategic nuclear forces, he added.

"There is no reason it can’t be used against the U.S.," Schneider said. "Its range is comparable to the early Polaris missiles which were our strategic deterrent in the 1960s."

The Kalibr is one of two main weapons systems that Russia plans to use in any future strikes on the United States. The second is the advanced Kh-101 air-launched cruise missile that can be armed with either conventional or nuclear warheads.

The Washington Free Beacon reported in 2015 that Russian bombers practiced cruise missile strikes on the United States from launch areas off the coast of Canada in September 2014

Last month, Russia President Vladimir Putin announced that Moscow will soon deploy a new hypersonic missile capable of defeating U.S. missile defenses. The new missile called Avangard was flight tested last month and traveled at a reported Mach 30—more than 20,000 miles per hour—while maneuvering and changing altitude.

Putin has stated that Russia may produce a land-based version of the Kalibr because of the U.S. pullout from the 1987 Intermediate-range Nuclear Forces Treaty.

Also in December, Igor Korotchenko, editor-in-chief of Russian magazine National Defense, stated that Russia could deploy its submarines close to the United States.

"Our submarines, too, might have surfaced suddenly some place in the Gulf of Mexico to shock America," Korotchenko said. "We have the corresponding forces of our submarine fleet there. We do not do that for the simple reason our purpose is not to show off in such a silly way, but to cope with the assigned tasks."

Russia claimed in state media earlier this year that in 2013 a Russian submarine sailed into the Gulf of Mexico undetected.

A Russian submarine officer asserted that an Akula-class nuclear-powered attack submarine armed with Kalibr cruise missiles came within "missile strike distance from one of the main bases of American submarines," an apparent reference to the Kings Bay submarine base in Georgia.

The Free Beacon reported in 2012 that the Akula-class submarine sailed in the Gulf of Mexico.

However, the chief of naval operations at the time, Adm. Jonathan W. Greenert, denied the incursion in a letter to Sen. John Cornyn (R., Texas). "Based on all of the source information available to us, a Russian submarine did not enter the Gulf of Mexico," Greenert said.

The Kalibr also comes in an export version known as the Klub that are deployed in a launch cannister disguised as a shipping container, making it an ideal missile to fire from the deck of a merchant vessel.