NEW DELHI (PTI): Navy Chief Admiral R Hari Kumar on Wednesday held extensive talks with Commander of the US Indo-Pacific Command, Admiral John Aquilino, focusing on major challenges emanating from China's increasing assertiveness in the Indo-Pacific and possible implications of the Ukraine crisis for regional security.

The top American commander also met Defence Minister Rajnath Singh and discussed pressing maritime security challenges in Indo-Pacific, people familiar with the development said.

Admiral Aquilino is in India to participate in the Raisina Dialogue, India's premier foreign policy and geo-economics conference.

It is learnt that the two commanders carried out a comprehensive review of bilateral naval cooperation and the security challenges in the Indo-Pacific, South China Sea and the Indian Ocean Region.

Admiral Kumar and Admiral Aquilino also delved into the possible implications of the Russian-Ukraine conflict for the Indo-Pacific region, the people cited above said.

The Navy Chief also held wide-ranging discussions with Gen Angus Campbell, Chief of the Defence Force of Australia, especially to mitigate security concerns in common waters of the Indian Ocean Region.

Army Chief Gen MM Naravane also held talks with Gen Campbell with a focus on ways to strengthen the defence cooperation between the two countries.

In an interactive session at the Raisina Dialogue, Admiral Aquilino said extensively referred to the conflict in Ukraine and said it is time for like-minded countries to prepare with a "sense of urgency" to deal with similar challenges.

"We are all concerned about what we watched in Ukraine. We watched unprovoked action to generate a war. This is a very concerning time as I look through the lens of global security," he said.

The top American commander also talked about the "no limits" friendship between Russia and China and said it was a matter of great concern.

Admiral Aquilino said like-minded countries must develop "great deterrence" by utilising all forms of technology and national power in all domains.

"We need to prepare with a sense of urgency," he said describing the Russian attack on Ukraine as the "most dangerous time in my lifetime".

The commander said there was a need for the countries in the Indo-Pacific to work together to deal with coercion.

Admiral Aquilino said that NATO (The North Atlantic Treaty Organisation) is increasing its strength in view of the Russian actions against Ukraine.

He also suggested that it could be a good model for the Indo-Pacific.

The US Indo-Pacific Command (INDOPACOM) is the oldest and largest combatant command of the US that is responsible for American military activities in the Indo-Pacific.

Defence Minister Singh visited the headquarters of the INDOPACOM in Hawai earlier this month.

People cited above said though India and the other three member countries of the Quad grouping have divergent views on the Russian attack on Ukraine, practical cooperation under the framework of the grouping will not be affected.

While the US, Japan and Australia have been severely critical of Russia's actions against Ukraine, India has not yet condemned the invasion.

"Defence cooperation has been a critical element of Indo-US relations. Towards ensuring free, open and inclusive Indo-Pacific, both the Admirals discussed avenues to further enhance the existing cooperation between two navies through capability enhancement and cooperative engagements," said an Indian Navy official.