The emergence of S-400 air defense systems near the Indo-China border could prompt Beijing to rethink its New Delhi countermeasures strategy.

An Indian defense official, who spoke on condition of anonymity, said it was seeking to urge Russia to speed up the production and delivery of the S-400 long-range air defense systems.

Russian media later said that Moscow agreed to speed up the contract, which is expected to deliver the first S-400 system to New Delhi in January 2021, nearly a year earlier than planned.

The United States has repeatedly said the deal could affect Washington's plans to transfer defense technology to New Delhi in the future, and threaten to punish it under the U.S. Anti-Rival Act through sanctions.

Many experts in India also expressed doubts about the effectiveness of the S-400 and its effectiveness.

Song Zhongping, a military commentator in Hong Kong, said the 400-kilometer range of the S-400 would be a significant threat to China in the Himalayas.

"If the S-400 system is deployed near the Actual Control Line (LAC) in Ladakh, it could threaten planes deep inside Chinese airspace. This will give Chinese commanders a headache, causing

Still, the Chinese military is not completely helpless against the S-400.

"The Chinese military has operated this system, they understand the weakness of the S-400, as well as how to blind or remove it from combat," Song added.

India and China agree to ban military aircraft from being present within 10 km of the LAC, unless prior notice is given to the other party.

Beijing-based military analyst Zhou Chenming said the threat from the S-400 system took a long time to become a reality, especially when Russia had postponed arms sales to foreign countries, including

"Operators need one to two years of training to achieve full combat readiness after handing over the weapons. The S-400 contract information is speeding up like a Chinese warning message.