Defence Minister Antoni Macierewicz looks on after a remembrance ceremony for the 2010 plane crash that killed Poland's President Lech Kaczynski and 95 others in Smolensk, in front of the Presidential Palace in Warsaw, Poland March 10, 2016. REUTERS/Kacper Pempel

WARSAW (Reuters) - Poland’s defense minister has said Russia continued to pose a serious threat to NATO and that Moscow was systematically preparing for aggression against the alliance.

Poland, a former Soviet satellite state, fears Russia is seeking to extend its influence beyond its borders after Moscow annexed Ukraine’s Crimea peninsula in 2014 and continues to support for armed separatists in eastern Ukraine.

Earlier this month, two Russian warplanes flew simulated attack passes near a U.S. guided missile destroyer which had just left the Polish port of Gdynia. A U.S. official said this was one of the most aggressive interactions between the two sides in recent memory.

“So far, all Russian behavior attests to systematic preparation for aggressive action,” Defense Minister Antoni Macierewicz told the Rzeczpospolita daily in an interview published on Tuesday.

“And it’s time to talk about it openly.”

Warsaw will host a NATO heads of state summit in July, where it will push for an increased military presence on the alliance’s eastern flank.

In 2014, NATO suspended cooperation with Russia over its role the conflict in Ukraine. Russia says deployment of significant NATO forces close to its borders would violate the 1997 NATO-Russia Founding Act.