Given the task definition and input, reply with output. In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.

In this Tuesday, April 12, 2016 photo provided by the U.S. Navy, a Russian Sukhoi Su-24 attack aircraft makes a low altitude pass by the USS Donald Cook in the Baltic Sea. U.S. officials said the guided-missile... (Associated Press) 
  
 In this Tuesday, April 12, 2016 photo provided by the U.S. Navy, a Russian Sukhoi Su-24 attack aircraft makes a low altitude pass by the USS Donald Cook in the Baltic Sea. U.S. officials said the guided-missile destroyer was operating in international waters 70 nautical miles off the Russian enclave... (Associated Press) 
  
 WASHINGTON (AP) — Russian attack planes buzzed a U.S. Navy destroyer in the Baltic Sea multiple times Monday and Tuesday, coming as close as an estimated 30 feet from the ship and twice passing below the ship's navigation bridge, U.S. officials said Wednesday. 
  
 The Russian Su-24 planes appeared unarmed but on Tuesday flew what the commander of the USS Donald Cook deemed to be a simulated attack profile. The Cook's commander judged the actions unsafe and unprofessional, but the ship took no action beyond trying unsuccessfully to communicate with the aircraft by radio, according to a statement by U.S. European Command. 
  
 The U.S. European Command, which oversees U.S. military operations in that area, said the Cook was conducting deck landing drills with an allied military helicopter when two Su-24s made numerous close-range and low-altitude passes Monday afternoon. One pass occurred while the helicopter was refueling on the Cook's deck. 
  
 "As a safety precaution, flight operations were suspended until the Su-24s departed the area," it said. 
  
 European Command did not identify the ally involved but other officials said the helicopter was Polish. 
  
 It was unclear when or if the U.S. government would formally protest the Russian actions, which come at a time of tensions between Washington and Moscow over Russia's annexation of Crimea, its military intervention in eastern Ukraine and fears among former Soviet states in eastern Europe that Russian aggression could threaten their independence. 
  
 White House press secretary Josh Earnest said the incident was part of a pattern of unsafe Russian aircraft action. 
  
 "This incident ... is entirely inconsistent with the professional norms of militaries operating in proximity to each other in international waters and international airspace," Earnest said. 
  
 "There have been repeated incidents over the last year where the Russian military, including Russian military aircraft, have come close enough to each other or have come close enough to other air and sea traffic to raise serious safety concerns. We continue to be concerned about this behavior," he said. 
  
 European Command released a Navy photo showing one Su-24 soaring past the Cook at close range. 
  
 A Navy video clip shows another low-altitude pass with a U.S. sailor shouting, "Below the bridge wing," meaning the Russian plane was flying below the level of the Cook's navigation bridge. 
  
 "We have deep concerns about the unsafe and unprofessional Russian flight maneuvers," European Command said in its written statement. "These actions have the potential to unnecessarily escalate tensions between countries, and could result in a miscalculation or accident that could cause serious injury or death." 
  
 It said U.S. officials are using diplomatic channels to address the matter. The incidents also are under review by the Navy. 
  
 The incident began Monday with a pair of Russian Su-24 planes making 20 close passes over the Cook, coming as close as 1,000 yards at an altitude of about 100 feet, according to a U.S. defense official. The official was not authorized to discuss some details by name and so spoke on condition of anonymity. 
  
 On Tuesday a Russian KA-26 submarine-hunting helicopter circled the Cook at low altitude seven times, taking photographs, the official said. About 40 minutes later, another pair of Su-24 attack planes, apparently unarmed, buzzed the Cook 11 times, the European Command statement said. At one point, at least one of the planes came within 30 feet of the ship, according to a Pentagon spokeswoman, Lt. Col. Michelle L. Baldanza. 
  
 The U.S. believes the Russian actions may have violated a 1970s agreement meant to prevent unsafe incidents at sea. The agreement was between the U.S. and the former Soviet Union but remains in force with Russia. 
  
 Officials said the Cook was operating in international waters 70 nautical miles off the Russian enclave of Kaliningrad. It had departed the Polish port of Gdynia on Monday. In April 2014 the Cook reported what it considered provocative actions by an apparently unarmed Russian Su-24 jet that made numerous low passes near the ship in the Black Sea near Romania. ||||| Media playback is unsupported on your device Media caption Navy video captures Russian flyby in mid-April 
  
 Two Russian planes flew close to a US guided missile destroyer almost a dozen times, American officials have said. 
  
 The Sukhoi SU-24 warplanes, in international waters in the Baltic Sea, had no visible weaponry and the ship took no action. 
  
 One official called the events on Monday and Tuesday "one of the most aggressive acts in recent memory". 
  
 The commander of the missile destroyer, the USS Donald Cook, described the flights as a "simulated attack". 
  
 The passes were "unsafe, potentially provocative" and "could have caused an accident," officials said in a release. 
  
 Image copyright US Navy Image caption The Russian Sukhoi Su-24 aircraft made very low passes by the USS Donald Cook 
  
 Image copyright US Navy Image caption A Russian Kamov KA-27 Helix surveys USS Donald Cook on 12 April 2016 
  
 At one point the jets were so close, about 9m (30ft), that they created wakes in the water around the ship. 
  
 The actions may have violated a 1970s agreement meant to prevent dangerous incidents at sea, but it is not clear whether the US is going to protest. 
  
 A Russian helicopter taking pictures also passed by the ship seven times. 
  
 The Donald Cook was conducting deck landing drills with an Allied military helicopter when the jets made their passes, according to a statement from the United States European Command. 
  
 Flight operations were suspended until the jets left the area. 
  
 The next day, a Russian KA-27 helicopter did circles at low altitude around the ship, followed by more jet passes. 
  
 The aircraft did not respond to safety warnings in English or Russian. 
  
 Analysis: Gary O'Donoghue, BBC News Washington 
  
 Image copyright US Navy Image caption The jets were so close they created wakes in the water near the ship 
  
 These close encounters of a military kind between the US and its allies and Russia have escalated significantly over the past two years, ever since Russia's annexation of Crimea and the substantial break down of relations between East and West. 
  
 They take various forms. They can be violations of national airspace; narrowly avoided mid-air collisions, close encounters at sea and simulated attack runs. 
  
 The incidents have taken place over a wide area - in and around the Baltic states; in the Baltic sea; the Black Sea and even close to Stockholm, when the Swedish authorities believed a Russian submarine had violated its territorial waters in 2014. 
  
 They are regarded by defence analysts as a flexing of muscle - a reminder that Russia has military might and cannot be pushed around. 
  
 But the frequency of such situations means many fear that a full on confrontation - be-it deliberate or accidental - is just a matter of time between the world's two great military powers. 
  
 "We have deep concerns about the unsafe and unprofessional Russian flight manoeuvres," the statement read. "These actions have the potential to unnecessarily escalate tensions between countries, and could result in a miscalculation or accident that could cause serious injury or death." 
  
 US officials are reviewing the incident. 
  
 A similar incident occurred last June, when Russian warplanes made close passes over a US destroyer in the Black Sea. 
  
 Russian media had reported at the time that the USS Ross was acting "aggressively" but the Department of Defense refuted that. ||||| WASHINGTON (Reuters) - Two Russian warplanes flew simulated attack passes near a U.S. guided missile destroyer in the Baltic Sea on Tuesday, the U.S. military said, with one official describing them as one of the most aggressive interactions in recent memory. 
  
 The repeated flights by the Sukhoi SU-24 warplanes, which also flew near the ship a day earlier, were so close they created wake in the water, with 11 passes, the official said on Wednesday. The planes carried no visible weaponry, the official said. 
  
 A Russian KA-27 Helix helicopter also made seven passes around the USS Donald Cook, taking pictures. The nearest Russian territory was about 70 nautical miles away in its enclave of Kaliningrad, which sits between Lithuania and Poland. 
  
 “They tried to raise them (the Russian aircraft) on the radio but they did not answer,” the official said, speaking on condition of anonymity, adding the U.S. ship was in international waters. 
  
 The U.S. military on Wednesday released photos and videos of the incidents. In one photograph, an SU-24 appears to pass at extremely low altitude over the Donald Cook’s bow. 
  
 The events were reminiscent of the Cold War, when a series of close calls led to a bilateral agreement aimed at avoiding dangerous interactions at sea that was signed in 1972 by then-Secretary of the Navy John Warner and Soviet Admiral Sergei Gorshkov. 
  
 The agreement prohibited "simulated attacks against aircraft or ships, performing aerobatics over ships, or dropping hazardous objects near them." The accord can be seen here: www.state.gov/t/isn/4791.htm 
  
 White House spokesman Josh Earnest said, “This incident ... is entirely inconsistent with the professional norms of militaries operating in proximity to each other in international water and international airspace.” 
  
 The incident came as NATO plans its biggest build-up in eastern Europe since the Cold War to counter what the alliance, and in particular the three Baltic states and Poland, consider to be a more aggressive Russia. 
  
 The Baltic states, Estonia, Latvia and Lithuania, which joined both NATO and the European Union in 2004, have asked NATO for a permanent presence of battalion-sized deployments of allied troops in each of their territories. A NATO battalion typically consists of 300 to 800 troops. 
  
 Moscow denies any intention to attack the Baltic states. 
  
 “We cannot treat this as anything else than provocation, yet another example of aggressive intentions towards NATO, towards the United States, towards Poland,” Poland’s Defense Minister Antoni Macierewicz told private radio RMF. 
  
 The USS Donald Cook had just wrapped up a port visit in the Polish city of Gdynia on April 11 and proceeded out to sea with a Polish helicopter on board. 
  
 The first incident took place on April 11, when two SU-24 jets flew about 20 passes near the Donald Cook, coming within 1,000 yards (meters) of the ship, at about 100 feet (30 meters) in altitude. 
  
 An U.S. Navy picture shows what appears to be a Russian Sukhoi SU-24 attack aircraft making a very low pass close to the U.S. guided missile destroyer USS Donald Cook in the Baltic Sea in this picture taken April 12, 2016 and released April 13, 2016. REUTERS/US Navy/Handout via Reuters 
  
 That was followed by even closer passes by the SU-24s the following day and the passes by the Russian helicopter. 
  
 The U.S. defense official said the commanding officer of the Donald Cook believed that Tuesday’s incident was “unsafe and unprofessional.” 
  
 The U.S. military’s European Command said in a statement that “U.S. officials are using existing diplomatic channels to address the interactions, while the incidents are also being reviewed through U.S. Navy channels.” 
  
 “These actions have the potential to unnecessarily escalate tensions between countries, and could result in a miscalculation or accident that could cause serious injury or death,” it said. 
  
 U.S. Representative J. Randy Forbes, who chairs the House Armed Services subcommittee on seapower, said in a statement that “U.S. naval activity in Europe must be expanded accordingly to address the threat posed by Russia’s international behavior.” 
  
 The U.S. Navy’s video of the incidents can be seen here: 
  
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In a move that American officials are calling "aggressive," "potentially provocative," "unprofessional," and simply "unsafe," Russian fighter jets and a helicopter buzzed a US warship in international waters Monday and Tuesday. The Guardian reports that US European Command says the encounters were "simulated attacks" on the USS Donald Cook and in the closest approach, a Russian Su-24 came within just 30 feet of the destroyer while it was conducting helicopter landing drills in the Baltic Sea just off the coast of Poland. The Navy says the aircraft didn't respond to safety warnings in English or Russian. A defense official tells the AP that a pair of Su-24s made around 20 close passes on Monday. On Tuesday, a helicopter taking photos circled seven times, followed by another pair of Su-24s that made almost a dozen passes, the official says. American officials say the Russian encounters count as "one of the most aggressive acts in recent memory," the BBC reports. Reuters notes that the encounters may have violated a Cold War-era agreement banning "simulated attacks against aircraft or ships, performing aerobatics over ships, or dropping hazardous objects near them." US officials say the incident is being addressed from diplomatic channels. There has been no official response from Moscow.