Defense Secretary Ashton B. Carter will focus on NATO issues for the next week. (Mark Wilson/Getty Images)

As NATO forces continue a slew of large-scale military exercises that have included amphibious operations and airborne drops across Eastern Europe and the Baltics, Defense Secretary Ashton B. Carter will spend the next week in the region pushing the alliance to ditch the Cold War playbook these exercises seem ripped from.

“The new playbook is to respond to the new security situation in Europe, including the situation posed by Russia’s own behavior,” Carter told reporters. “It’s not like it was in the old days. We are looking at a NATO response that is much more mobile [and] much more agile.”

Carter’s comments come as the United States weighs whether to place heavy weapons — including tanks and infantry fighting vehicles — and up to 5,000 troops in Poland, amid a precarious security situation in eastern Ukraine and escalating tensions with Russia.

The troops in Poland would augment NATO’s Very High Readiness Joint Task Force, known as the “spearhead force,” whose units have been placed throughout the region as a crisis-response force.

“This is another step toward building a greater U.S. presence in Poland and the region,” Defense Minister Tomasz Siemoniak told the Polish news agency PAP last week.

Carter, who will witness the task force’s capabilities firsthand during a new set of exercises in the coming week, stressed that the force will be part of a strong and balanced approach to dealing with the new challenges facing NATO, including “hybrid warfare” of the likes seen in Crimea last year as well as the extremist threat percolating in northern Africa.

Hybrid warfare “is one of the dimensions of our adaptations and very important [for] countries surrounding Russia that don’t want to be susceptible to the kind of thing that happened in Crimea,” Carter said.

About 65,000 U.S. troops are stationed throughout Europe, down from about 400,000 at the height of the Cold War.

“This is not the Europe of the Cold War; this is the Europe of today, and we are trying to make sure NATO is prepared to deal with the threats of today,” said a senior defense official, who was not permitted to talk to the media and so spoke on the condition of anonymity.

Yet the notion of placing more U.S. troops and equipment in Poland, which would be one of the more aggressive moves by the Pentagon since the Cold War, has antagonized Russia. Last week, Russian President Vladimir Putin announced the addition of 40 intercontinental ballistic missiles to his country’s already large stockpile.

“We hope that reason will prevail and the situation in Europe will be prevented from sliding into a new military confrontation which may have dangerous consequences,” the Russian Foreign Ministry said in a statement last week.

Carter’s visit to the region coincides with the tail end of BALTOPS, a massive NATO exercise that began earlier this month and involves almost 6,000 troops from 17 countries, on land and sea and in the air.

The trip is an “opportune time to go to Europe and take stock of the very changed security environment, threats coming from the east and from the south, to make sure NATO is poised to meet those threats in the best possible way,” said another official, who was also not allowed to speak to the media and discussed the visit on the condition of anonymity.

The BALTOPS exercise, which ended Saturday, peaked last week with a practice amphibious landing in Ustka, Poland — 100 miles west of Russia’s strategic warm-water naval base in Kaliningrad.

In moves that appeared to coincide with the exercises, Russian aircraft buzzed participating U.S. warships, with one jet coming within a few hundred feet of the USS Jason Dunham, a destroyer. Additionally, NATO jets based in Estonia have intercepted Russian aircraft flying near restricted airspace more than 10 times since the jets were first stationed there seven weeks ago.