Aerial view of the Pentagon building photographed on Sept. 24, 2017.
CNN  — 

Russian President Vladimir Putin’s new $5 billion weapons deal with India — a key American ally – to sell an advanced S-400 air defense system is just the latest open challenge by Russia to US defense dominance.

The move comes as the Pentagon is trying to reshape its own military priorities to deal with both Russian and Chinese military advances — countries the Pentagon says are now “near peer competitors” with the US military under President Donald Trump.

The S-400 is one of Russia’s premier air defense systems, which it is also trying to sell to Turkey, another key US ally. The spread of the S-400 capability underscores the type of worry US commanders have. In the field, it functions with a virtual umbrella of radars and missiles that can limit the ability of the US military to operate freely and without restrictions in combat.

That reshaping to focus on Russia and China by the Pentagon is moving forward on several fronts. The Pentagon is soon expected to issue an updated military strategy report further focusing on that re-shaping of US forces.

The finishing touches are also being put on recommendations by Gen. Joseph Dunford, chairman of the Joint Chiefs of Staff, to shift US troops and equipment around the world from an almost sole focus fighting terrorism in the Middle East to a greater focus on countering those two nations. That could shift US efforts back toward training more for potential armored conflict rather than small-unit counterterrorism operations.

And a classified proposal to increase military seaborne and air “show of force” efforts around the globe against China, and possibly Russia, is being considered. One US defense official described this part of the effort as a way of “pressuring” both nations to understand they would always have to deal with the US military on a global basis despite any of their own technological advances or regional military operations.

All of this is leading to potential reductions is US forces in Africa and the Middle East. The head of US Central Command insists it’s not a problem for his operations in Persian Gulf, Iraq, Syria and Afghanistan.

“We’re in a new era of great power competition and we have been planning accordingly,” said Gen. Joseph Votel.

The Russian arms sale to India is just one of Moscow’s efforts to flex its military profile and make it more challenging for the US to deal with their military. There is growing concern that Russian submarine improvements will make it more difficult for the US to detect those submarines operating submerged — giving the Russians more covert freedom of movement even off US coastlines. The Russians also are fielding a cruise missile from submarines in the Mediterranean that “can range any one of the capitals in Europe,” according to Adm. James Foggo, commander of US naval forces in Europe and NATO’s Allied Joint Force Command Naples.

Speaking about Russian naval advances, Foggo said, “That’s a concern to me, and it’s a concern to my NATO partners and friends. So we should know where they are at all times.”

Last month, Foggo sounded a warning about Russian submarine technology.

“I think Russian submarines today are perhaps some of the most silent and lethal in the world, with the exception of our own,” he said.

Foggo is overseeing a massive NATO-led exercise in Norway and other areas of Northern Europe aimed at specifically showcasing the ability of NATO to challenge Russia if it were to invade a European neighbor. The exercise will include 31 countries, 45,000 troops, 150 aircraft, 60 ships, and up to 10,000 vehicles.

But Russia is also challenging NATO and the US with another ground-launched cruise missile that the US has long said violates an arms control treaty. The US has tried pressuring the Russians into giving up the missile, but to no avail. Defense Secretary James Mattis would not say how the Trump administration plans to respond to Russia on the missile.

“We will respond as we think is appropriate,” said Mattis.

Advances in submarine technology and other new weapons won’t stop the US military, defense officials insist, but these programs are beginning to drive US military on how to deal with Russia and China. Both of those nations have been working on hypersonic missiles, for example, which fly at five times the speed of sound. While the US is also researching hypersonic weapons, for now, it’s a race to see who will be successful first. For now, the US has no defense against a hypersonic attack, if one were to come.