US officials are reportedly preparing to announce restrictions on Russian military flights over America, US officials at the State Department and Pentagon told the Wall Street Journal.
Both Russia and the US are among the 34 signatories of the Treaty on Open Skies, which allows ratified member states to conduct unarmed aerial surveillance flights over each other's territory.
The flights are intended to foster transparency about military activity.
Tensions rose in August, when a Russian plane operating under the Open Skies agreement conducted a low-level observation flights over US cities including Washington and Bedminster, where Donald Trump was on a 17-day break at the Trump National Golf Club.
But those flights aren't the cause of the new restrictions, officials added.
Instead, they say recent restrictions imposed on flights over the Russian exclave of Kaliningrad by the Kremlin are in violation of the Open Skies treaty.
The US delegation is expected to announce reciprocal countermeasures during an Open Skies meeting in Vienna.
While the treaty permits a flight range of 3,418 miles (5,500km) per flight, the Kremlin enforced a "sub-limit" of of 310 miles (500km) over Kaliningrad.
Pentagon officials said it requires around 745 miles (1,200km) to cover the entirety of Kaliningrad, meaning the restriction forces treaty members to allocate two flights which would otherwise have been used to observe other parts of Russia.
“We want to induce Russia to come back into compliance with the treaty,” a senior State Department official told the paper.
“Open Skies is part of a gradual breakdown in relations,” they added. “Russia wants to renegotiate the European security relationship.
In May, Russia performed similar Open Skies flights over the UK.