(ABC NEWS) -- A Russian fighter jet came within several feet of a U.S. Air Force reconnaissance aircraft flying over the Baltic Sea on Monday, in an encounter the American pilot determined was unsafe.

The incident occurred Monday morning as an RC-135 reconnaissance aircraft flew in international airspace above the Baltic Sea.

It was intercepted by a Russian Su-27 Flanker fighter jet that approached at a high rate of speed.

The Russian fighter “came within several feet” of the RC-135, according to Capt. Joseph Alonso, a spokesman for U.S. European Command.

The pilot of the American aircraft determined that the Russian aircraft’s actions were “unsafe” because of its “high rate of closure speed and poor control of the aircraft.”

The intercept lasted a few minutes.

A defense official familiar with the incident said the Russian aircraft came alongside the RC-135 and made some unpredictable and erratic maneuvers, at one point flying underneath the reconnaissance aircraft.

According to Alonso, the RC-135 was flying in international airspace with its transponder switched on, making it identifiable to other aircraft.

Various factors go into ruling whether an incident should be ruled unsafe including distance, speed, altitude, rate of closure and visibility.