Despite repeated calls by the Malaysian authorities to countries to hand over radar data, many are hesitant to do so.
Although the information could provide more clues regarding the missing Malaysia Airlines jet, it may also reveal the countries' air defence intelligence, said security and aviation experts.
This has led to inertia among partners to help solve the mystery of Flight MH370.
"You can show what you have got, but at the same time, you don't want to show what you don't have and expose your weakness," said researcher Ian Storey of Singapore's Institute of Southeast Asian Studies.
"There is still a lot of distrust, enormous sensitivities in sovereignty issues in this region... many are still very reluctant to exchange and share intelligence data unless it is between two parties that have a deep level of trust."
Unlike the United States, Britain, Australia and New Zealand, countries in the region do not have a pact to share their signals intelligence, including satellite and radar data.
Despite militaries' fledgling push to promote multilateral efforts to train and work together, "habits of secrecy kick in", said Dr Storey.
A former Singaporean military radar specialist, who declined to be named, said: "Based on how much and how far your radar can see, potential foes can gauge how prepared you are and act accordingly to counter your preparedness."
Malaysian Prime Minister Najib Razak stressed last week that Malaysia overrode national security concerns to share military radar data with foreign experts, in a bid to deflect criticisms that it was hiding information.
But the move also exposed shortcomings in Malaysia's management of its radars - it failed to react to the radar blips that were MH370, said the radar specialist.
Likewise, India's radars covering the Andaman and Nicobar islands reportedly failed to pick up the flight.
The episode has shown that "someone dropped the ball and left a big hole in national security in the region", said aviation expert Chris Yates.
Still, he said that the level of secrecy between regional countries goes deeper than he had thought.
"It is just data and information on a particular aircraft, at a particular time and on a particular day," he said.
"There shouldn't be difficulty in checking radar tapes... it comes down to the fundamental level of trust."
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