The US military has held preliminary discussions about moving a powerful missile defense system to Germany to boost European defenses, according to two sources familiar with the issue, a move that experts said could trigger fresh tensions with Moscow, Reuters reported.

The tentative proposal to send the Terminal High Altitude Area Defense (THAAD) system to Europe predates U.S. President Donald Trump’s decision to withdraw from the 2015 Iran nuclear accord, and comes amid a broader push to strengthen Europe’s air and missile defenses.

The U.S. Defense Dept said no such action had been decided.

“There are currently no plans to station THAAD systems in Germany. We do not discuss potential future military planning, as we would not want to signal our intent to potential adversaries. Germany remains among our closest partners and strongest allies,” said Pentagon spokesman Eric Pahon.

Deploying another U.S. defensive system to Europe could reassure NATO allies in southern Europe already within striking range of Iran’s missiles, said one military official from that region.

Talk of deploying a THAAD system in Europe also comes against the backdrop of rising tensions between the West and Russia.