The US remained "watchful" over developments along India's frontier with China as it cannot take its eyes off the regional security issues, a senior American official said on Wednesday in the backdrop of the over 29-month border standoff in eastern Ladakh that has significantly frayed ties between the two neighbours.

Rear Admiral Michael L Baker, the Defence Attache at the US Embassy, also said that it is important to be "mindful" of Chinese actions in the South China Sea as well, even as he described India-US defence ties as the "cornerstone" of the overall bilateral relations.

"I cannot speak in this forum on a real, detailed level about what we may or may not observe. But I will tell you that it is certainly an important area for us. We do remain watchful," he told a small group of reporters.

His remarks came when asked whether the US has been tracking the developments along India's border with China and how the US views the lingering conflict playing out in the coming months.

"We do work closely with India to exchange our views on this area to make sure that we have a clear understanding of what we think may be happening and I think it is a space that, for both India and the United States, we are going to remain watchful over time. We cannot take our eye off the regional security issues," he said.

In response to another question on China's increasing military muscle flexing in the South China Sea, Rear Admiral Baker said it is important to assist countries across the region to have a choice of security partners.

"They have a very aggressive stance in the South China Sea. The United States has a pretty clear public position on this too. That's something we need to be mindful and watchful of," the senior defence official said.

He said the countries in the region could partner with someone like India or the US or both. "That is the key to ensuring that the Indo-Pacific remains free and open, which is the mutual goal for both India and the United States."

Rear Admiral Baker said the robust defence trade, numerous high level dialogues and increasing number of military exercises in the sea, air and the land are further strengthening the defence relations between India and the US.

"I think we have a lot of trust between our countries and between our militaries. We conduct more exercises together in India than any other country. We operate together at sea routinely and these kinds of interactions deepen trust and familiarity everyday," he said.

Rear Admiral Baker also noted that India and the US are carrying out joint maritime patrols and operating in the same operational space in the North Arabian Sea as well as in the Pacific.

"We know each other so well with a strong level of trust," he added.

Asked how the US sees increasing collaboration between Russia and China in the backdrop of the war in Ukraine, Rear Admiral Baker, said the amount Moscow is getting from "that other partner" is not in accordance with international law or rules.

"We would call on both of them to take proper stand in that war in Ukraine immediately," he said and referred to comments by US Secretary of State Antony Blinken that if Russian President Vladimir Putin "stops fighting, the war ends and if Ukraine stops fighting, Ukraine ends".

On whether the US was assisting India to deter China, he did not give a direct reply but said, India has an "incredibly bright future" as it has "superb geography and high mountains" which are critical for defence.

He also mentioned India's large landmass and access to the sea saying, "these are key elements for becoming a highly powerful country."

On the situation in the Indian Ocean, he said China has been having a pretty continuous maritime presence in the region for at least a decade now.

"That's been a pretty consistent presence," he said.

Indo-US defence ties have been on an upswing in the last few years.

In June 2016, the US designated India a "Major Defence Partner" paving way for sharing of critical military equipment and technology.

The two countries have also inked key defence and security pacts over the past few years, including the Logistics Exchange Memorandum of Agreement (LEMOA) in 2016 that allows their militaries to use each other's bases for repair and replenishment of supplies.

The two sides also signed COMCASA (Communications Compatibility and Security Agreement) in 2018 which provides for interoperability between the two militaries and provides for the sale of high-end technology from the US to India.

In October 2020, India and the US sealed the BECA (Basic Exchange and Cooperation Agreement) agreement to further boost bilateral defence ties.

The pact provides for sharing of high-end military technology, logistics and geospatial maps between the two countries.