The Baltic NATO ally summoned Russia's envoy to demand an explanation, but Moscow claims the incursion was an emergency call which is being "politicized."
Russian jets have been caught near NATO skies twice recently.
It is a busy summer for Russia and allied forces around the Baltic Sea.
Russian jets often fly near NATO territory, prompting scrambles. How is it able to make these reconnaissance flights?
The unmanned X-37B, which resembles a miniature space shuttle, touched down at 7:47 a.m. EDT on a runway formerly used for landings of the now-mothballed space shuttles.
Estonia's Ministry of Defence claims Russian jets violated its airspace four times in 2016.
Russia's has sought to strengthen its capabilities in the south as a priority.
Russian jets will not enjoy unrestricted passage into and cannot fly over Iraqi cities.
The Kremlin is aware of Erdogan's request to meet but would not accept or decline it.
Russia sent an advanced missile system to Syria on Wednesday to protect its jets operating there.
The government is hoping to have drone owners registered before Christmas.
Greece is unable to react to Turkey's trespassing into its territory due to lack in military funding.
The country denied any violation of international airspace.
Russia's top navy admiral plans to strengthen forces in Crimea and the Arctic over the next 15 years
The base will launch drones to patrol Russia's eastern waters and assist Russian navy
NATO says airspace incursions are up 300% this year in dangerous return to Cold War tactics that could risk MH17-style disaster
The ship's presence was preceded by the appearance of two Russian bomber jets in Portuguese as the Finnish president warned of a new Cold War
North America has intercepted over 50 Russian fighter jets encroaching on U.S. and Canadian airspace in the past five years