Crown Prince Maha Vajiralongkorn will succeed the king, Prime Minister Prayuth Chan-ocha said in a televised address.
While addressing the 14th ASEAN-India summit, the PM noted that growing radicalism and spread of extreme violence are the other security threats.
This could be their last meeting as leaders of the two countries with Obama's second term as US President coming to an end in November.
Modi held talks with Abe after arriving in the Laotian capital to attend the Association of Southeast Asian Nations-India and the East Asia summits that will take place on Thursday.
The Summit comes at a time when China is flexing its muscle to tighten its grip over the disputed South China Sea.
India on Saturday extended $500 million (Rs 3,328 crore) Line of Credit to Vietnam for facilitating deeper defence cooperation with the south east Asian nation, as the two countries elevated their ties to a Comprehensive Strategic Partnership to respond to emerging regional challenges.
Prime Minister Narendra Modi on Saturday visited the historic Pagoda temple in Hanoi and the stilt house where revered Vietnamese leader Ho Chi Minh lived, apart from enjoying fishing with his Vietnamese counterpart Nguyen Xuan Phuc.
India has ended regulatory uncertainty: Modi assures Malaysia.
Both countries will advance maritime security and strengthen disaster response in the region, says Modi.
Addressing the Indian diaspora on the second day of his three-day visit to Malaysia, Modi said India draws strength from its diversity and that his government is working to create an environment where enterprise flourishes and everybody gets basic needs like roof, sanitation, water, health care and education.
The PM unveiled the bronze statue of Vivekananda amid cheers from the more than 2,000 Indians, most of them ethnic Indian-Malaysians.
"We often thought of terrorism as a peripheral problem for this region. The barbaric terrorist strikes in Paris, Ankara, Beirut, Mali and on the Russian aircraft is a stark reminder that its shadow stretches across our societies and our world, both in recruitment and choice of targets," Modi said in his remarks at the East Asia Summit.
He suggested evolving specific plans for cooperation with the 10-memeber grouping in key areas of maritime security, counter-piracy and humanitarian and disaster relief.
The national flag was in the background of Modi and Abe's customary handshake at the Summit and was hoisted on a stand next to that of Japan.
"Reform is not an end in itself. Reform for me is just a way station on the long journey to the destination. The destination is the transformation of India," he said.
Terrorism, trade and South China Sea dispute are expected to dominate discussions at the 13th ASEAN-India Summit likely to begin later today with Prime Minister Narendra Modi and other Southeast Asian leaders reviewing the Association of Southeast Asian Nations-India cooperation and charting out its future direction.
The two Indians, who were not identified, have been taken to a military camp for questioning, The Nation quoted the police as saying.
The 28-year-old man, who was not identified and was arrested from his rented apartment in Nong Chok district in a suburb in eastern Bangkok, was also found in possession of multiple passports.
Police confirmed the explosion, near a shrine at a major Bangkok road, was from a bomb but no one has yet claimed responsibility for the attack.
The Indian economy is expected to return to the pre-crisis growth trajectory of about 9 per cent in a couple of years.