Frontline bases of the Indian army and the air force along the nearly 3,500 km border with China were put on high alert on Wednesday in view of the worst border clash between Indian and Chinese troops in Galwan Valley that left 20 Army personnel dead and several injured, government sources said.
The Indian Navy has also been asked to raise its alert-level in the Indian Ocean Region where Chinese Navy has been making regular forays.
The Indian Army has already rushed in additional troops and weaponry to all its key frontline bases and formations along the Line of Actual Control (LAC) in Arunachal Pradesh, Uttarakhand, Himachal Pradesh and Ladakh, they said.
"The rules of engagement will be different from now onwards. The prime minister has spelt out the broad policy about it," a top military official told PTI on the condition of anonymity.
Sending a strong message to China, PM Modi said India wants peace but is capable of giving a befitting reply if instigated. It was his first reaction to the violent clashes in Galwan Valley.
Defence Minister Rajnath Singh met Prime Minister Narendra Modi in the evening and is learnt to have briefed him about steps being taken to boost military strength along the LAC to deal with any eventuality.
The Indian Air Force has raised the alert level in all its frontline bases tasked to keep an eye on the LAC, the sources said.
The decision to raise the alert level of the three forces was taken at a high-level meeting Defence Minister Rajnath Singh held with Chief of Defence Staff Gen Bipin Rawat and the three service chiefs, sources said.
They said the Navy is increasing its deployment in the Indian Ocean Region to send across a strong message to the Chinese Navy.
The clash in Galwan Valley on Monday night is the biggest confrontation between the two militaries after their 1967 clashes in Nathu La in 1967 when India lost around 80 soldiers while over 300 Chinese army personnel were killed.
The sources said the armed forces will respond with a "firm approach" to any act of aggression by the Chinese Army henceforth.
They said Indian Navy is also expected to adopt an aggressive approach in dealing with Chinese naval forays into the Indian Ocean region.