By Jonathan Marcus BBC defence correspondent

India is sabre-rattling on a grand scale.

It has made no secret of its continuing frustration at what it sees as Pakistan's failure to control activist groups in Kashmir.

India and Pakistan have amassed troops along their border

This month's attack on the parliament building in Delhi has clearly inflamed Indian public opinion and forced the government's hand.

Major reinforcements have been sent to the border, air patrols have been stepped up and ground-to-ground missile systems have been deployed to forward positions from where they could strike targets in Pakistan.

The scale of the Indian military build-up is intended to send a blunt signal to the government in Islambad.

India has watched closely from the side-lines as the Afghan crisis unfolded.

It saw Pakistan's central role as an ally of Washington, though many in India viewed their own country as a more natural partner in President Bush's struggle against international terrorism.

War on terror

This explains the extraordinary passions that have been aroused by the attack on the Indian parliament.

India wants Pakistan to eradicate militant Kashmiri groups

But as well as passion there is cold political calculation.

Pakistan may have a key role in US thinking for the time being, but many Indian analysts believe that their own security interests must be served.

And since the struggle against global terrorism is firmly in the headlines, India is moving to capitalise on the moment to see what gains it can make.

Above all, it wants international pressure brought on Pakistan to restrain anti-Indian groups in Kashmir.

The US decision to designate two militant Pakistani groups as terrorist organisations is a small victory for the Indian Government.

But it clearly believes that the time has come to put maximum pressure on its opposite number in Islamabad.

The danger is that the preparations for war could risk turning any minor skirmish into full-scale conflict.