SRINAGAR, India/NEW DELHI (Reuters) - India said on Monday it had the right to respond when and where it chose to a deadly attack on an army base in Kashmir, after blaming Pakistan for the raid that killed 18 soldiers.

The assault, in which four gunmen burst into a brigade headquarters in the town of Uri before dawn on Sunday, was among the deadliest in the disputed Himalayan region and has sharply raised tensions between the nuclear-armed rivals.

Army officials said the critically wounded had been flown to New Delhi and one had died in hospital. Most of dead and wounded suffered severe burns after their tents and temporary shelters caught fire from incendiary ammunition while they were sleeping.

Senior Indian politicians, including Home Minister Rajnath Singh who called Pakistan “a terrorist state”, were quick to warn of action against Islamabad, putting pressure on Prime Minister Narendra Modi to take a tough line.

The head of military operations of the Indian army, Lieutenant General Ranbir Singh, said India had the desired capability to respond, without elaborating.

“We reserve the right to respond to any act of the adversary at a time and place of our own choosing,” Ranbir Singh told reporters, adding that the army had seized equipment from the Uri base with Pakistani markings.

Pakistan accused India of apportioning blame before it had properly investigated.

“Pakistan categorically rejects the baseless and irresponsible accusations being leveled by senior officials in Prime Minister Modi’s government,” the prime minister’s foreign affairs adviser said in a statement late on Sunday.

The Pakistan army said that India was promoting a “hostile narrative”.

Kashmir, divided between India and Pakistan since 1947, is at the heart the neighbors’ seven decades of mutual distrust. Two of their three wars since independence from Britain have been fought over the region.

India’s portion of Kashmir has been under a major security lockdown during more than two months of protests sparked by the July 8 killing of a popular young commander of a Kashmiri militant group.

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LIMITED OPTIONS

India’s options to hit back at Pakistan appeared limited, as they carried the risk of escalation.

India held back from military retaliation when a Pakistan-based group killed 166 people in a 2008 rampage through Mumbai, for fear of igniting a broader conflict, and opted instead for a diplomatic offensive to isolate Islamabad.

An attack on another Indian base near the border with Pakistan in January also drew a measured response, but the casualty toll was lower than in Sunday’s raid.

The concern is that Modi’s government has signaled a lower threshold for retaliation against attacks from Pakistan than the previous Congress government, which adopted a policy of “strategic restraint”.

Among the military options that India could consider are artillery strikes on Pakistani army positions it alleges are used for helping militants cross over into its part of Kashmir, military experts say.

But that would imperil a 2003 ceasefire along the frontier, although it has frayed in recent years.

A second option on the table would be sending special forces inside Pakistan to attack guerrilla training camps, although that was a high-risk gamble that could easily go wrong, the experts said.

Modi held talks with leaders of his ruling Bharatiya Janata Party at a cabinet meeting on how to respond.

“Our first priority is to fortify every defense base and it is shocking that one of our strategic locations was hit,” a senior aide told Reuters.

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EYEBALL TO EYEBALL

Indian troops searched three ravines that cut across the de facto border in mountainous terrain near Uri, which a senior army official said the militants were believed to have used to sneak into Indian-administered territory.

Reinforcements were also sent to patrol one of the world’s most heavily militarized frontiers, where Indian and Pakistani forces stand eyeball to eyeball in places and sometimes exchange fire, the army official added.

A weekly bus service between Srinagar in Indian-administered Kashmir and Muzaffarabad, the capital on the Pakistani side, operated as normal on Monday, however. The bus passed through Uri and passengers waited at the frontier ready to cross.

The United States, United Kingdom and France condemned the attack and said they stood with India in its fight against “terrorism”.

India was ranked fifth in the world in terms of military strength, according to a 2015 assessment by Credit Suisse based on data from Stockholm International Peace Research Institute and Global Firepower, compared to 11th for Pakistan.

Pakistan has an estimated 120 nuclear warheads against India’s 110, according to the Arms Control Association.

India has long blamed Pakistan for playing a role in the 27-year long insurgency against its rule in Jammu and Kashmir, its only Muslim-majority state.

Singh, the army general, said Sunday’s assault bore the hallmarks of Pakistan-based militant group Jaish-e-Mohammed. But he did not offer evidence tying the attack to the group.

Led by Islamist hardliner Maulana Masood Azhar from Pakistan’s Punjab province, Jaish-e-Mohammed was blamed for the January air base raid as well as a 2001 attack on India’s parliament that nearly led to war.

Pakistan denies sending fighters into Indian-administered Kashmir.

No one has yet claimed responsibility and other Pakistan-based militant organizations like Laskhar-e-Taiba have been accused of plotting attacks in India.

Pakistan has called on the United Nations and the international community to investigate atrocities it alleges have been committed by Indian security forces in Kashmir.

The UN is preparing to hold its annual general assembly in New York, where Kashmir is likely to be on the agenda.