Secretary of State John Kerry said that under US military rules of engagement, the Navy ship that Russian military jets buzzed in the Baltic Sea this week could have opened fire.
The guided-missile destroyer USS Donald Cook reported that pairs of Russian SU-24 attack planes made numerous close-range passes on Monday and Tuesday.
In remarks to CNN Espanol in Miami, Kerry condemned the Russian actions and said that ‘under the rules of engagement’ it ‘could have been a shootdown’. 

On at least one occasion an SU-24 came within an estimated 30 feet of the Cook, which was in international waters about 70 nautical miles from the Russian enclave of Kaliningrad, which hosts Russian military forces.
The repeated flights by the SU-24 warplanes were so close, they created wakes in the water, with 11 passes, a US Defense official said.
The planes appeared to be unarmed.
A Russian KA-27 Helix helicopter also made seven passes around the Cook, taking pictures.  The Cook did not respond except to unsuccessfully query the Russian pilots by radio.
‘They tried to raise them (the Russian aircraft) on the radio but they did not answer,’ the official said, speaking on condition of anonymity, adding the US ship was in international waters.
In all cases a military commander has the authority to defend his or her ship, plane or other unit.  The commander is expected to use his or her best judgment under the circumstances to determine whether the ship faces an imminent threat. The official said the commanding officer of the Cook believed that Tuesday’s incident was ‘unsafe and unprofessional,’ but cautioned that a formal US military review of the matter was under way.
White House spokesman Josh Earnest said the U.S. raised its concerns through its military defense representative at the U.S. Embassy in Moscow.

The Cook did not respond except to unsuccessfully query the Russian pilots flying the SU-24 (file photo) by radio