"The US aircraft was operating in international airspace and at no time crossed into Russian territory," Laura Seal, a Defense Department spokeswoman, said on Saturday.

She noted that the incident occurred on Thursday and the US aircraft in question was an RC-135.

"This unsafe and unprofessional air intercept has the potential to cause serious harm and injury to all aircrews involved," Seal added. "More importantly, the unsafe and unprofessional actions of a single pilot have the potential to unnecessarily escalate tensions between countries."

The news comes after the US military officials claimed that Sukhoi Su-24 planes had multiple simulated attack passes on Monday and Tuesday near the US Donald Cook destroyer in neutral waters of the Baltic.

Dismissing the action as reckless or provocative, Russia said its aircraft observed all required safety measures when flying over the US warship.

"After detecting the ship within their visibility range, the Russian pilots diverted from it with all safety precautions," said Russian Defense Ministry spokesman Igor Konashenkov.

The US Navy sent the Donald Cook to the Baltic Sea along with three other vessels last week "to boost security in Europe."

Washington believes the overflights breach a 1970s agreement which was designed to prevent unsafe incidents at sea.

The incident occurred as tensions are on the rise between the US and Russia over the ongoing conflicts in Ukraine and Syria.

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