AT SEA - SEPTEMBER 25, 2011:  In this handout released by the U.S. Navy, the U.S. Navy guided-missile destroyer USS Gravely (DDG 107) is underway during the multinational UNITAS Atlantic 53-2012 exercise conducted in the western Caribbean Sea  September 25, 2011 at sea. In a response to a alleged chemical weapons attack on its own people by the Syrian regime the USS Mahan, the USS Barry, the USS Ramage, and the USS Gravely, all Arleigh Burke-class destroyers carrying Tomahawk land-attack missiles, are en route or in position in the eastern Mediterranean for a possible strike on Syrian military assets on August 28, 2013.  (Photo by U.S. Navy via Getty Images)
U.S. Navy/Getty Images North America/Getty Images
AT SEA - SEPTEMBER 25, 2011: In this handout released by the U.S. Navy, the U.S. Navy guided-missile destroyer USS Gravely (DDG 107) is underway during the multinational UNITAS Atlantic 53-2012 exercise conducted in the western Caribbean Sea September 25, 2011 at sea. In a response to a alleged chemical weapons attack on its own people by the Syrian regime the USS Mahan, the USS Barry, the USS Ramage, and the USS Gravely, all Arleigh Burke-class destroyers carrying Tomahawk land-attack missiles, are en route or in position in the eastern Mediterranean for a possible strike on Syrian military assets on August 28, 2013. (Photo by U.S. Navy via Getty Images)
Now playing
00:53
U.S. destroyer sails by Russian warship
(L/R): Head of Dutch Military Intelligence and Security Service Onno Eichelsheim, Minister of Defence Ank Bijleveld and British ambassador Peter Wilson attend a press conference of the Dutch Military Intelligence and Security Service (MIVD) at The Hague, The Netherlands, on October 4, 2018. - Dutch intelligence thwarted a Russian cyber attack targeting the global chemical weapons watchdog in April and expelled four Russian agents, the government said. The Russians set up a car full of electronic equipment in the car park of a hotel next to the Organisation for the Prohibition for Chemical Weapons in The Hague in a bid to hack its computer system, it said. (Photo by Bart Maat / ANP / AFP) / Netherlands OUT        (Photo credit should read BART MAAT/AFP/Getty Images)
BART MAAT/AFP/Getty Images
(L/R): Head of Dutch Military Intelligence and Security Service Onno Eichelsheim, Minister of Defence Ank Bijleveld and British ambassador Peter Wilson attend a press conference of the Dutch Military Intelligence and Security Service (MIVD) at The Hague, The Netherlands, on October 4, 2018. - Dutch intelligence thwarted a Russian cyber attack targeting the global chemical weapons watchdog in April and expelled four Russian agents, the government said. The Russians set up a car full of electronic equipment in the car park of a hotel next to the Organisation for the Prohibition for Chemical Weapons in The Hague in a bid to hack its computer system, it said. (Photo by Bart Maat / ANP / AFP) / Netherlands OUT (Photo credit should read BART MAAT/AFP/Getty Images)
Now playing
01:11
Russia denies western accusations of attacks
putin response russian spy lon orig bks_00003009.jpg
BBC
putin response russian spy lon orig bks_00003009.jpg
Now playing
01:30
Reporter confronts Putin about spy poisoning
The UK will expel 23 Russian diplomats from the country after concluding that the Russian state is responsible for the attempted murder of former Russian agent, Sergei Skripal and his daughter Yulia in Salisbury on March 4th.  They will have one week to leave.   "For those who seek to do us harm, my message is simple. You are not welcome here."
Bowtie TV
The UK will expel 23 Russian diplomats from the country after concluding that the Russian state is responsible for the attempted murder of former Russian agent, Sergei Skripal and his daughter Yulia in Salisbury on March 4th. They will have one week to leave. "For those who seek to do us harm, my message is simple. You are not welcome here."
Now playing
01:08
Theresa May: UK will expel 23 Russian diplomats
A Russian flag flies next to the US embassy building in Moscow on July 31, 2017. (MLADEN ANTONOV/AFP/Getty Images)
MLADEN ANTONOV/AFP/Getty Images
A Russian flag flies next to the US embassy building in Moscow on July 31, 2017. (MLADEN ANTONOV/AFP/Getty Images)
Now playing
01:04
Suspected Russian spy worked inside US embassy
 Steven Seagal (R) delivers a press conference with Costa Rican President, Oscar Arias (out of frame), on February 11, 2009, at the presidential residence in San Jose. Seagal and Arias met to talk about the possibility of real estate and film industry investments in Costa Rica. AFP PHOTO/ Mayela LOPEZ (Photo credit should read MAYELA LOPEZ/AFP/Getty Images)
MAYELA LOPEZ/AFP/Getty Images
Steven Seagal (R) delivers a press conference with Costa Rican President, Oscar Arias (out of frame), on February 11, 2009, at the presidential residence in San Jose. Seagal and Arias met to talk about the possibility of real estate and film industry investments in Costa Rica. AFP PHOTO/ Mayela LOPEZ (Photo credit should read MAYELA LOPEZ/AFP/Getty Images)
Now playing
02:30
Putin appoints Steven Seagal for diplomat job
russia new nuclear weapons putin chance lkl vpx _00002715.jpg
Russian Defense Ministry
russia new nuclear weapons putin chance lkl vpx _00002715.jpg
Now playing
01:09
Russia releases video of new nuclear weapons
SALISBURY, ENGLAND - JULY 05:  A police officer stands by a cordon in place at Queen Elizabeth Gardens in Salisbury after a major incident was declared when a man and woman were exposed to the Novichok nerve agent on July 5, 2018 in Salisbury, England. The couple, named locally as Dawn Sturgess 44, and Charlie Rowley, 45 were taken to Salisbury District Hospital on Saturday and remain there in a critical condition. In March Russian former spy Sergei Skripal and his 33-year-old daughter Yulia were poisoned with the Russian-made Novichok in the town of Salisbury. British Prime Minister Theresa May has accused Russia of being behind the attack on the former spy and his daughter, expelling 23 Russian diplomats in retaliation. (Photo by Jack Taylor/Getty Images)
Jack Taylor/Getty Images
SALISBURY, ENGLAND - JULY 05: A police officer stands by a cordon in place at Queen Elizabeth Gardens in Salisbury after a major incident was declared when a man and woman were exposed to the Novichok nerve agent on July 5, 2018 in Salisbury, England. The couple, named locally as Dawn Sturgess 44, and Charlie Rowley, 45 were taken to Salisbury District Hospital on Saturday and remain there in a critical condition. In March Russian former spy Sergei Skripal and his 33-year-old daughter Yulia were poisoned with the Russian-made Novichok in the town of Salisbury. British Prime Minister Theresa May has accused Russia of being behind the attack on the former spy and his daughter, expelling 23 Russian diplomats in retaliation. (Photo by Jack Taylor/Getty Images)
Now playing
02:02
Russia denies involvement in poisoning attacks
Reuters
Now playing
00:54
May: Nerve agent poisoning deeply disturbing
 A CNN team accessed the Malaysia Airlines flight 17 (MH17) crash site, July 30, 2014 and found evidence that there are still belongings at the site, including pieces of the plane .
Raja Razek/CNN
A CNN team accessed the Malaysia Airlines flight 17 (MH17) crash site, July 30, 2014 and found evidence that there are still belongings at the site, including pieces of the plane .
Now playing
00:49
Investigators: MH17 downed by Russian missile
Yulia Skripal poses for the media during an interview in n London, Wednesday May 23, 2018. Yulia Skripal says recovery has been slow and painful, in first interview since nerve agent poisoning. (Dylan Martinez/Pool via AP)
Dylan Martinez/AP
Yulia Skripal poses for the media during an interview in n London, Wednesday May 23, 2018. Yulia Skripal says recovery has been slow and painful, in first interview since nerve agent poisoning. (Dylan Martinez/Pool via AP)
Now playing
02:34
Daughter of poisoned ex-spy: Lucky to be alive
GOOGLE EARTH
Now playing
01:28
Russia blames Israel for strikes on Syria
CNN PHOTO ILLUSTRATION/GETTY IMAGES
Now playing
02:36
Why Hungary is looking more and more like Russia
A Russian flag flies next to the US embassy building in Moscow on March 27, 2018. (MLADEN ANTONOV/AFP/Getty Images)
MLADEN ANTONOV/AFP/Getty Images
A Russian flag flies next to the US embassy building in Moscow on March 27, 2018. (MLADEN ANTONOV/AFP/Getty Images)
Now playing
02:26
Russia retaliates, expels 60 US diplomats
Presidential candidate, President Vladimir Putin addresses the crowd during a rally and a concert celebrating the fourth anniversary of Russia's annexation of Crimea at Manezhnaya Square in Moscow on March 18, 2018. / AFP PHOTO / POOL / Alexander Zemlianichenko        (Photo credit should read ALEXANDER ZEMLIANICHENKO/AFP/Getty Images)
ALEXANDER ZEMLIANICHENKO/AFP/AFP/Getty Images
Presidential candidate, President Vladimir Putin addresses the crowd during a rally and a concert celebrating the fourth anniversary of Russia's annexation of Crimea at Manezhnaya Square in Moscow on March 18, 2018. / AFP PHOTO / POOL / Alexander Zemlianichenko (Photo credit should read ALEXANDER ZEMLIANICHENKO/AFP/Getty Images)
Now playing
01:35
Russia votes: How the day unfolded
Russian President Vladimir Putin delivers a speech during a meeting with Russian athletes and team members, who will take part in the upcoming 2018 Pyeongchang Winter Olympic Games, at the Novo-Ogaryovo state residence outside Moscow on January 31, 2018. / AFP PHOTO / SPUTNIK / Alexey NIKOLSKYALEXEY NIKOLSKY/AFP/Getty Images
ALEXEY NIKOLSKY/AFP/AFP/Getty Images
Russian President Vladimir Putin delivers a speech during a meeting with Russian athletes and team members, who will take part in the upcoming 2018 Pyeongchang Winter Olympic Games, at the Novo-Ogaryovo state residence outside Moscow on January 31, 2018. / AFP PHOTO / SPUTNIK / Alexey NIKOLSKYALEXEY NIKOLSKY/AFP/Getty Images
Now playing
03:47
How do you become president of Russia?

Story highlights

At least six close encounters this year between US and Russian ships, planes

Analysts see the risky maneuvers as a strategy to challenge the U.S., intimidate allies

(CNN) —  

The repeated close encounters between Russian and U.S. warships and planes may not be an accident.

That’s the view of analysts who are coming to believe that the risky Russian maneuvers – there have been at least six close calls this year – are part of Vladimir Putin’s strategy aimed at challenging the U.S.’s global position and intimidating its European allies.

“The Russians believe that if they do a show of force, that they achieve results that promote their interests. In this case, it is a certain degree of intimidation,” retired Army Gen. Wesley Clark told CNN.

Clark, who was NATO’s supreme allied commander until 2000, added that it “shows that they (the Russians) are willing to stand up to the United States.”

The Kremlin has been angered lately by NATO’s effort to bolster its eastern flank amid increased Russian military activity in the region.

The Russian-U.S. military episodes have taken place all over the world, from the Pacific Ocean and Mediterranean to the Baltic and Black Seas.

In the most recent incident, a Russian ship last week came within 150 yards of a U.S. Navy vessel, the USS San Jacinto, that was sailing in the eastern Mediterranean. The U.S. Navy described the maneuver in a statement as unsafe, “erratic” and “aggressive.”

A few weeks earlier, the Russian Neustrashimyy-class frigate came within 315 yards of the USS Gravely.

And in April, two Russian fighter jets flew within 30 feet of the USS Donald Cook while it was sailing in the Baltic Sea, an action that U.S. Secretary of State John Kerry warned could have led to the jets being shot down.

U.S. officials say Russian warship came dangerously close

Kerry told CNN en Español that “under the rules of engagement, that could have been a shoot-down, so people need to understand that this is serious business.”

Many see the spate of incidents not as accidents but as intentional moves by the Russian president.

Heather Conley, of the Center for Strategic and International Studies, a DC-based think tank, told CNN after the April incident that Putin is trying to send a message to America’s partners.

“To America’s European allies, the Kremlin is messaging that the U.S. cannot protect them from Russia if Russia wants to do something to them militarily,” she said.

The latest close calls come as the U.S. and NATO take steps to reinforce the alliance’s eastern flank in the days leading up the summit of leaders, to take place in Warsaw, Poland on July 8-9.

Russians “barrell roll” over another U.S. Air Force plane

Last month, NATO announced the alliance would deploy four multinational battalions of about 1,000 troops each to Estonia, Latvia, Lithuania and Poland as part of a bid to deter Russia in the wake of Moscow’s intervention in Ukraine and annexation of Crimea in 2014.

The Kremlin has lambasted NATO’s eastern activity and has announced plans to deploy advanced nuclear-capable missiles in its European enclave of Kaliningrad by 2019, according