A Russian spy ship was spotted patrolling off the coast of Delaware on Tuesday — the same day it emerged that the Kremlin secretly deployed new cruise missiles and buzzed a US Navy destroyer, according to a report.

The Russian ship SSV-175 Viktor Leonov was in international waters, 70 miles from Delaware, as it sailed north at 10 knots, a US official told Fox News. It was not immediately clear where it was headed.

Russia deployed ground-launched cruise missiles to two locations inside the country in December, a US official told Fox News later Tuesday.

The New York Times reported that the Obama administration had previously seen the missiles as a violation of a 1987 arms control treaty between the US and Russia that banned ground-launched intermediate-range missiles.

Russia had secretly deployed the SSC-8 cruise missile that Moscow has been developing and testing for several years, the Times reported.

The missile deployment presents a major challenge for President Trump, who has vowed to improve relations with Russian strongman Vladimir Putin and to pursue future arms accords.