A top admiral has said that the US Navy will 'consider' whether two fatal collisions this summer could have been the result of a cyber attack.

Admiral John Richardson, the chief of naval operations, said on Monday that there were 'no indications right now' that the two ships were hacked, but added investigators 'will consider all possibilities'.

The shocking possibility emerged as the Navy ordered a broad investigation into the performance and readiness of the Pacific-based 7th Fleet.

Early Monday, the USS John S. McCain collided with an oil tanker in Southeast Asian waters, leaving 10 American sailors missing and several others injured.

It was the second major collision in the last two months involving the Navy's 7th Fleet, after seven sailors died when the USS Fitzgerald and a container ship collided in waters off Japan on June 17.

Early Tuesday, three navies were hunting desperately for the McCain's 10 missing sailors as the search and rescue mission dragged into a second day.

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Admiral John Richardson, the chief of naval operations, said on Monday that investigators will consider whether 'cyber intrusion or sabotage' compromised two crashed warships

The collision east of Singapore between the 505-foot destroyer guided missile destroyer and the 600-foot Alnic MC ripped a gaping hole (above) in the destroyer's hull

Seven sailors died when the USS Fitzgerald (pictured) and a container ship collided in waters off Japan in June

Defense Secretary Jim Mattis said on Monday (pictured above) that Navy Adm. John Richardson will call for a pause in operations and seek a deeper look at how the Navy trains and certifies its forces that are operating around Japan

This is the second collision involving a ship from the Navy's 7th Fleet in the Pacific in two months. Seven sailors died in June when the USS Fitzgerald and a container ship hit each other in waters off Japan

As part of an ongoing investigation into the USS Fitzgerald incident the Captain, the Executive Officer and Master Chief Petty Officer were removed from duty last week.

'The collision was avoidable, and both ships demonstrated poor seamanship,' the Navy's 7th Fleet said in a statement, noting that 'flawed' teamwork among those assigned to keep watch contributed to the collision.

The Navy said the three had shown 'inadequate leadership.' Separately, seven junior officers were relieved of their duties because they had shown 'poor seamanship' and bad teamwork, 7th Fleet spokesman Cmdr. Clay Doss said on Friday.

Stricken: The USS Fitzgerald is moved into a dry dock at Yokosuka, Japan on July 17 where it will be repaired following it collision with a freighter the month prior

Meanwhile , aircraft from the USS America and ships and aircraft from the navies of Malaysia and Singapore were focusing their search for the missing 10 sailors from the USS John S. McCain on an area east of the city-state where the two vessels collided early the day before at an approach to a busy shipping lane.

The McCain is now docked at Singapore's naval base. The 7th Fleet said the McCain's crew is emptying compartments that flooded when the collision ruptured its hull.

Richardson will call for a pause in operations and seek a deeper look at how the Navy trains and certifies its forces that are operating around Japan, Defense Secretary Jim Mattis said on Monday.

'He has put together a broader inquiry to look into these incidents,' Mattis said, referring to the two recent collisions and other accidents at sea.

Mattis spoke to reporters in Amman, Jordan, where he is traveling.

Vessels and aircraft from the US, Indonesia, Singapore and Malaysia are currently searching for the 10 missing sailors.

Four other sailors were evacuated by a Singaporean navy helicopter to a hospital in the city-state for treatment of non-life threatening injuries. A fifth was taken to the hospital by ambulance after the destroyer arrived in Singapore under its own power.

There was no immediate explanation for the collision.

Royal Malaysian Navy personnel look for missing sailors of the US guided-missile destroyer USS John S. McCain off Johor coastal area on Tuesday

The Malaysian navy joined with search teams from Singapore and the US as the search entered a second day on Tuesday morning

The Alnic MC tanker, pictured here outside Singapore, collided with the USS John S. McCain in the early hours of Monday morning

Ten sailors are missing and five were injured after the USS John S McCain was involved in a collision with a 600-foot oil tanker on Monday morning, the Navy said

A picture of the US guided-missile destroyer after the collision shows the ship riding low in the water with a hole in its side near its waterline

Singapore, at the southernmost tip of the Malay Peninsula, is one of the world's busiest ports and a US ally, with its naval base regularly visited by American warships.

The McCain had been heading to Singapore on a routine port visit after conducting a sensitive freedom-of-navigation operation last week by sailing near one of China's man-made islands in the South China Sea.

The collision east of Singapore between the 505-foot destroyer guided missile destroyer and the 600-foot Alnic MC ripped a gaping hole in the destroyer's hull.

The Navy's 7th Fleet said 'significant damage' to the McCain's hull resulted in the flooding of adjacent compartments including crew berths, machinery and communications rooms. A damage control response prevented further flooding.

The destroyer was damaged on its port side aft, or left rear, in the 5.24am collision about 4.5 nautical miles from Malaysia's coast but was able to sail on to Singapore's naval base.

Malaysia's Maritime Enforcement Agency said the area is at the start of a designated sea lane for ships sailing into the Singapore Strait, one of the world's busiest.

A photo tweeted by Malaysian navy chief Ahmad Kamarulzaman Ahmad Badaruddin showed a large rupture in the McCain's side near the waterline. Janes, a defense industry publication, estimated the hull breach was 10 feet wide.

Another US naval vessel, the amphibious assault ship USS America, arrived in Singapore and deployed Osprey aircraft and Seahawk helicopters. It was helping with damage control on the McCain and with the search for the missing sailors. It also will feed and house sailors from the stricken ship.

One of the injured sailors, Operations Specialist 2nd Class Navin Ramdhun, posted a Facebook message telling family and friends he was okay and awaiting surgery for an arm injury. He told The Associated Press in a message that he couldn't say what happened. 'I was actually sleeping at that time. Not entirely sure.'

The Singapore government said no crew were injured on the Liberian-flagged Alnic, which sustained damage to a compartment at the front of the ship some 23 feet above its waterline. There were no reports of a chemical or oil spill.

Several safety violations were recorded for the oil tanker at its last port inspection in July, one fire safety deficiency and two safety-of-navigation problems. The official database for ports in Asia doesn't go into details and the problems were apparently not serious enough for the Liberian-flagged vessel to be detained by the port authority.

The US Navy review will look at the 7th Fleet's performance, including personnel, navigation capabilities, maintenance, equipment, surface warfare training, munitions, certifications and how sailors move through their careers.

'The chief of naval operations' broader inquiry will look at all related accidents, incidents at sea' involving ships of the 7th Fleet, Mattis said. 'This is a broader look at what is happening.'

Richardson wants to ensure there aren't bigger problems in the fleet that may be masked by the high pace of operations there and budget uncertainties, according to a Navy official. Beyond the tragedy of the lost lives and the hundreds of millions of dollars being spent on repairs, Richardson wants to be sure that the Navy is able to meet the maritime demands, particularly in the Pacific region, the official said.

After the collision, the John McCain sailed under its own power and headed to port at Changi Naval Base in Singapore

Richardson has directed Adm. Phil Davidson, head of the Navy's Fleet Forces, to lead the investigation. Davidson will assemble a panel of officers to help with the investigation and will have the full use of the Navy's office of the inspector general as well as the safety center.

In the June collision, the Fitzgerald's captain was relieved of his command and other sailors were being punished after the Navy found poor seamanship and flaws in keeping watch contributed to the collision. An investigation into how and why the Fitzgerald collided with the other ship was not finished, but enough details were known to take those actions, the Navy said.

US President Donald Trump expressed concern for the McCain's crew. Returning to Washington from his New Jersey golf club, he responded, 'That's too bad' when reporters shouted questions to him about the McCain. Later, Trump tweeted that 'thoughts and prayers' are with the McCain's sailors.

The McCain is named after US Sen. John McCain's father and grandfather, who were both US admirals. It's based at the 7th Fleet's homeport of Yokosuka, Japan. It was commissioned in 1994 and has a crew of 23 officers, 24 chief petty officers and 291 enlisted sailors, according the Navy's website.

McCain said on Twitter that he and his wife, Cindy, are 'keeping America's sailors aboard the USS John S McCain in our prayers tonight - appreciate the work of search & rescue crews.'