"We are aware of the vessel's presence," Lt. Col. Valerie Henderson, a spokeswoman for the Defense Department, told NBC News in an email. "It has not entered U.S. territorial waters. We respect freedom of navigation exercised by all nations beyond the territorial sea of a coastal State consistent with international law."
The ship, the Viktor Leonov, is expected to sail down the east coast and head to the Caribbean, according to Fox News. The White House has not commented on the presence of the ship.
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Although the Russian vessel hasn't broken any international laws with its presence, several Connecticut lawmakers have expressed concern over its proximity in light of the 2016 election hacks and outstanding questions surrounding Trump's former national security adviser's communications with Russia.
Rep. Joe Courtney, D-Connecticut, who serves on the Armed Services Committee and is the ranking member of the Seapower and Projection Forces Subcommittee, called it an "unacceptable, aggressive action."
"A Russian spy ship patrolling 30 miles from the Groton SUBASE underscores that the threats posed by a resurgent Russia are real," Courtney said in a press release.
On Wednesday, Sen. Chris Murphy, D-Connecticut, tweeted that Russia "is acting like it has a permission slip to expand influence" and "test limits" by placing a ship so close to the United States.
"While this is not wholly unprecedented, it's part of a series of aggressive actions by Russia that threaten U.S. national security and the security of our allies," Murphy, the ranking Democrat on the Foreign Relations Subcommittee on Europe and Regional Security Cooperation, said in a statement.
Republican members of the Homeland Security and Governmental Affairs Committee, which has primary oversight of the Homeland Security Department, did not immediately respond to a requests for comment. Sen. Rand Paul, R-Kentucky, who is on the committee, declined to comment.
Murphy asserted that the move was disconcerting as it came just a one day after it was reported that Russia secretly deployed a cruise missile in what officials have called a violation of a Cold War-era treaty and not long after Russian aircraft buzzed a U.S. destroyer in the Black Sea.
"President Trump and his administration must end their silence and immediately respond to these threats to our national security," Murphy said.