Admiral John Richardson, the US Navy's top officer, said Monday he hopes for a "normalization" of relations with Moscow in the Baltic Sea, where Russian jets have buzzed US planes and ships.

The latest incident came Friday, when a Russian SU-27 intercepted a US RC-135 reconnaissance plane flying in international airspace over the Baltic Sea.

It was the second such incident in recent weeks and the Pentagon called the encounter "unsafe and unprofessional."

In April, the US Navy released video of Russian aircraft flying very close to the USS Donald Cook, including in a "simulated attack profile."

"It just increases the chance for some kind of a tactical miscalculation," Richardson told Pentagon reporters.

"It just sort of raises the overall tension in the region, so we look for sort of normalization there."

He called on Moscow to abide by a maritime agreement, signed by US and Soviet powers in 1972, to avoid naval mishaps and prevent any such event from escalating.

"We continue to advocate for that," Richardson said.

Still, he downplayed the idea of there being any aggressive intent during the recent incidents.

"I don't think the Russians are trying to provoke an incident," he said. "I think they are trying to send a signal."

Moscow has expressed its displeasure about the proximity of US ships and planes to its borders.

Russia's annexation of Crimea and its support of pro-Russian separatists in eastern Ukraine have sent tensions soaring between Russia and the United States.

In a bid to ease fears of Russian aggression against Eastern Europe, NATO has deployed thousands of additional troops in the region and increased patrols and exercises.