(WASHINGTON) — Defense Secretary Lloyd Austin said Wednesday that he spoke with Russia’s defense minister about what he called “risky” behavior by Russian fighter jet pilots who the U.S. says caused an American drone to crash into the Black Sea near Ukraine.

“This hazardous episode is a part is part of a pattern of aggressive, risky, risky and unsafe actions by Russian pilots in international airspace,” Austin said at a news conference with Joint Chiefs Chairman Mark Milley.

“I just got off the phone with my Russian counterpart, Minister Shoigu. As I’ve said repeatedly, it’s important that great powers be models of transparency and communication. And the United States will continue to fly and to operate wherever international law allows. And it is incumbent upon Russia to operate as military aircraft in a safe and professional manner,” he said.

Austin would not get into the content of his call with Sergei Shoigu, but emphasized the importance of keeping lines of communication open.

“I think it’s really key that that we’re able to pick up the phone and engage each other,” he said.

Asked if the incident — during which the U.S. says one Russian jet collided with the MQ-9 Reaper drone’s propeller — constitutes an act of war, Milley said he would not go that far, saying the U.S. does not know if the collision itself was deliberate.

“We know that the intercept was intentional. We know that the aggressive behavior was intentional. We also know it was very unprofessional and very unsafe,” Milley said. “The actual contact of the fixed-wing Russian fighter with our UAV, the physical contact of those two, not sure yet, that remains to be seen.”

Russia has denied any collision.

“As far as an act of war goes, I’m not gonna go there. Incidents happen. And, and clearly, we do not seek armed conflict with with Russia. And, and I believe that at this point, we should investigate this incident and move on from there, but we will continue to exercise our rights in international airspace,” he continued.

The drone is about 4,000-5,000 feet under the Black Sea, and recovery will be “very difficult,” according to Milley. He said that while the U.S. doesn’t have any ships in the region, “we do have a lot of allies and friends in the area. And we’ll work through recovery operations.”

Austin said the Pentagon is still working to declassify images of the interception, but would not say when that might happen.

“We are still going through videos and photographs to ascertain what we can release, what we can provide. But in terms of what the video shows, we remain confident in the facts that we have conveyed thus far,” Austin said.

Earlier, in an interview on ABC’s “Good Morning America,” National Security Council spokesperson John Kirby said the incident between a Russian jet and a U.S. drone over the Black Sea “at the very least looks like this was just reckless behavior by a Russian pilot.”

Asked by co-anchor George Stephanopoulos if this was just a “dumb” move as one U.S. Air Force official stated, Kirby said, “that’s what it looks like right now.”

He said the message from the U.S. to the Russian ambassador called into the State Department Tuesday was, “don’t do this again.”

“We’re not minimizing this. I mean, you don’t bring in the Russian ambassador because you’re failing to take something seriously, we are taking it seriously and the message was don’t do this again. We’re going to continue to fly in international airspace over international waters. Where this drone was, that’s going to continue and we expect the Russians to observe international law and to not interfere with our legal operations,” Kirby said.

Kirby wouldn’t go into details when asked if he’s concerned if the drone technology could fall into Russian hands, but that the U.S. is working to recover the drone from the Black Sea, admitting that will be a challenging task.

“I can tell you we’re comfortable that should anything be taken by the Russians, their ability to exploit useful intelligence will be highly minimized. That said it’s our property and obviously we’re looking – we’re looking to see what we can do to maybe recover — that will be challenging in the Black Sea, it’s very, very deep water, but it’s our property,” he said.

Asked how the U.S. can prevent this kind of incident from happening again, Kirby said it comes down to “lines of communication staying open.”

“We have ways of communication with the Russians directly, and that’s a good thing. That’s one way to try and minimize the risk of miscalculation,” he said.

Kirby said the White House is “absolutely” concerned about the Russians escalating in other ways while its forces are stalled in Ukraine.

“Escalation concerns have been with us since the beginning of this war, George. And you don’t know exactly what Mr. Putin will do on any given day or how he will react to any outcomes on the battlefield,” Kirby said.

ABC News’ Justin Gomez contributed to this report.

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