The Indonesian government is to deploy fighter planes and warships to disputed waters off the island of Borneo, along its border with Malaysia.
By Jonathan Kent
BBC, Kuala Lumpur
Tensions have been growing since the Malaysian state petroleum corporation, Petronas, moved to grant exploration rights to the Anglo-Dutch firm Shell.
Both Indonesia and Malaysia claim rights to the region, which is thought to be rich in oil.
The two nations say they hope to resolve the dispute peacefully.
According to Indonesia's chief navy spokesman, the country will never let an inch of its land or a drop of its ocean fall into the hands of foreigners.
The scheduled deployment of three warships and four F16 fighters to the area off the east coast of Borneo will certainly lend weight to those words.
However, it is unlikely that the two countries will come to blows.
Indonesian President Susilo Bambang Yudhoyono and the Malaysian leader, Abdullah Badawi, spoke on the telephone early on Monday and agreed to hold talks at foreign ministerial level.
In the interim, President Yudhoyono is due to visit the disputed area.
His itinerary is expected to include a tour of camps holding thousands of Indonesians who have left Malaysia because of an operation to expel undocumented workers.
They have gathered in the border region and there are concerns for their health.
The migrant issue has also strained relations between the neighbours, with Malaysia wanting the workers back through legal channels, and accusing Jakarta of slowing their return.
The last territorial dispute between the two countries - over the islands of Sipadan and Ligatan, also off Borneo's east coast - was resolved peacefully through the International Court of Justice in the Hague.