Amid high tensions with Russia, the United States’ European missile defense shield is scheduled to go live Thursday after nearly a decade of preparations, Reuters reported. The missile defense shield was originally presented as a protection against Iranian rockets, but Russia views it as a provocation encroaching on its sphere of influence in Europe.

“We now have the capability to protect NATO in Europe,” said Robert Bell, a NATO envoy of U.S. Secretary of Defense Ash Carter. “The Iranians are increasing their capabilities, and we have to be ahead of that. The system is not aimed against Russia.”

The U.S. missile shield is stationed at an air base in Deveselu, Romania, and will be run under NATO command. Washington said it was also working to construct a second site in Redzikowo, Poland, that should become operational in 2018.

Russia announced Tuesday it was developing intercontinental ballistic missiles capable of piercing the U.S. missile shield. The Kremlin vowed in 2015 to retaliate should the NATO system become operational.

Russian state-backed media have already painted the missile defense shield as “symbolic” in nature, but Russia sees ballistic missiles as one of its top external threats. The Kremlin has also moved to reinforce its western and southern military flank divisions.

The operation of the missile shield is likely to further exacerbate relations between Moscow and Washington, which have been tense since Russia’s illegal annexation of Crimea from Ukraine in March 2014. Russia has argued that since the historic deal was agreed to in 2015 to curb Iran’s nuclear program, the missile shield is no longer a necessity.

“Ballistic missile defense sites could pose threats to the stability and strategic assets of the Russian Federation,” Ambassador to NATO Alexander Grushko told Reuters in April.

The U.S. has argued that missile proliferation is a growing threat despite the deal reached with Iran.

"More and more countries are trying to develop or acquire ballistic missiles. Moreover, missile technology is becoming more sophisticated, lethal and accurate, and increasing in range," NATO spokeswoman Carmen Romero told the Associated Press. "For us to discount or ignore that very real missile threat would be irresponsible."

The missile shield is based on a radar system that tracks missiles and fires interceptors to destroy any potential threat. The European missile shield plan was relaunched by President Barack Obama in 2009 after being agreed to under George W. Bush in 2007.