Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: Washington (CNN) A Russian spy ship sits 30 miles off the coast of Connecticut, a US defense official told CNN, while an armed Russian warplane recently carried out a "mock attack" against a US ship. This is the farthest north the Russian spy vessel has ever ventured, according to US defense official. CNN reported that the Leonov, which conducted similar patrols in 2014 and 2015, was off the coast of Delaware Wednesday, but typically it only travels as far as Virginia. The ship is based with Russia's northern fleet on the North Sea but had stopped over in Cuba before conducting its patrol along the Atlantic Coast and is expected to return there following its latest mission.It is the farthest north the Russian spy ship has venturedThe vessel is outfitted with a variety of high-tech spying equipment 
 Question:The development coincided with reports that _ had deployed a land-based intermediate range cruise missile, a move that one official labeled a violation of the 1987 arms control treaty.

Russian