The Russian exercise, known as Zapad, or West, occurs every four years and will take place this year in western Russia, including Belarus and the Russian enclave of Kaliningrad.
The U.S. military estimates that 70,000 to 100,000 Russian troops could take part in the exercise, the officials said, adding that the Russian military could also take the opportunity to upgrade certain equipment permanently stationed in the region. Specifically, the officials said that they expect the Russian missile defenses in Kaliningrad to be permanently upgraded with nuclear-capable Iskander ballistic missile systems.
Located on the Baltic Sea, Kaliningrad provides Russia with a warm-water port and acts as a de facto wedge between Poland and the Baltic states: Latvia, Estonia, Lithuania. The Pentagon has become increasingly wary of advanced Russian surface-to-air and ballistic missile deployments in Kalinigrad as their increasing ranges and radar signatures could affect U.S. and NATO military operations.
The Iskander system — which can hit targets more than 100 miles from its launch site — has been deployed to Kaliningrad before. A permanent placement there, however, could prompt the Baltic States to increase their antimissile defenses to counter the Iskander’s capabilities, including its ability to potentially launch long-range cruise missiles.
In response, several countries in the region are considering additional ground-based air defenses, the defense officials said, adding that the United States also could deploy Patriot surface-to-air missile batteries during the Zapad exercise if needed. The Patriot is capable of intercepting aircraft and ballistic missiles.
“We will deploy whatever capability is necessary here,” said Defense Secretary Jim Mattis on Wednesday during a visit to Lithuania to reaffirm the U.S. commitment to NATO and shore up support for the Baltic states. “We will talk to the leaders of each of the [NATO] nations and we’ll work this out in Brussels.”
Mattis said he had “no concerns” about the upcoming Zapad exercise, adding that’s it routine and he hopes “it stays routine.”
In October, the Lithuanian military said it was looking at positioning a Patriot system as part of the Lithuania-based multinational NATO battalion sometime this year. That battalion, led by the Germans, first arrived in January. The Patriot has also been deployed to Poland in the past.
Mattis addressed the Zapad exercise while speaking alongside Lithuanian President Dalia Grybauskaitė.
“Any buildup like that is simply destabilizing,” he said after being asked by reporters.
Mattis is spending the day meeting alongside his Baltic counterparts and will also visit U.S. and German troops at a training base 45 miles outside the capital of Vilnius.
In response to Russia’s annexation of Crimea in 2014 and its continued intervention in Ukraine, the United States has more than tripled its defense spending for its European command. Currently there are more than 20,000 U.S. troops Europe, including two brigade combat teams and another rotational brigade deployed to deter Russia. Additionally, NATO has placed four multinational battalions led by the United States, Canada, the United Kingdom and Germany in Latvia, Estonia, Lithuania and Poland.
Russia has called the troop increase and expanded NATO deployments as acts of aggression and as railed against some of the larger multinational exercises near its borders.
“I would just say I have too much respect for the Russian Army to think they actually believe that there’s any offensive capability,” Mattis said of U.S. and NATO forces in Europe. “They know and the world knows it’s a defensive and we deploy only defensive systems to make sure sovereignty is respected.”
In February, Mattis told the 28-nation NATO alliance in Brussels that it must pay its fair share for the alliance’s collective defense, following President Trump’s polarizing remarks about NATO on the campaign trail.
“Americans cannot care more for your children’s future security than you do,” Mattis said in his first speech to NATO since becoming defense secretary.
Currently, only five countries spend the alliance’s suggested target of two percent of their gross domestic product on defense spending: Britain, Poland, Estonia, Greece and the United States. On Wednesday, Mattis lauded Lithuania’s decision to increase its military spending to meet the two percent goal in the coming years.
While Trump voiced doubts about NATO — calling the alliance “obsolete” before he was elected — the president has since reversed his tone. Trump is expected to attend a May 25 NATO summit in Brussels where he will likely ask his counterparts to increase spending and work harder to combat terrorism.