Russian officials this week warned of retaliation if America places tanks and weapons near Russian borders in NATO countries.

“If heavy U.S. military equipment, including tanks, artillery batteries and other equipment really does turn up in countries in eastern Europe and the Baltics, that will be the most aggressive step by the Pentagon and NATO since the Cold War,” declared General Yuri Yakubov, the Russian defense ministry official. “Russia will have no option but to build up its forces and resources on the Western strategic front.”

After Russia invaded Ukraine in March 2014, NATO countries close to Russia requested help and protection from their allies. Russian officials frightened leaders in Latvia and Estonia after they announced Moscow is ready to defend ethnic Russians and Russian speakers in the former Soviet states. Given Poland’s disastrous history, their leaders have already enhanced the defense program.

Last year, Vice President Joe Biden and NATO leaders promised protection and security, but not much happened. NATO countries welcomed the news of American weapons and tanks to protect them from a possible Russian invasion.

“We think that at least part of it [Abrams and Bradleys] will be in Lithuania and we are in a process preparing our military infrastructure, so it could be used for such pre-positioning,” claimed Juozas Olekas, Lithuania’s defense minister, adding,

It is almost ready. We have been in talks with our American allies that it would be purposeful to locate the equipment here on permanent basis, in order to increase our security and support the soldiers stationed here. If the decision is taken, it will be very positive for our security.

It is the first time America has increased its presence in Europe since the end of the Cold War. The U.S. will spread weapons and 5,000 troops in Bulgaria, Estonia, Latvia, Lithuania, Romania, and Poland. All of these countries were once Soviet states or satellite states.

“If something happens, we can’t wait days or weeks for more equipment,” insisted Latvian Defense Minister Raimonds Vejonis. “We need to react immediately.”

Over the weekend, Latvian authorities arrested two Russian activists who attempted to enter a military base. The two men “carried the St. George flag of the Russian military and anti-NATO leaflets as they climbed over a wall at the Adazi military base on June 10 while training exercises between Latvian and U.S. forces were being conducted.”

Dmitry Peskov, a spokesman for the Kremlin, refused to comment on the reports.