Historically, the key dilemma facing Singapore's defence planners has been how to build a force capable of dealing simultaneously with current security threats while anticipating future challenges, amid limited defence resources.
In the 1960s and 1970s, the 1G SAF (Singapore Armed Forces) focused on capability development of individual services.
The next generation in the 1980s and 90s reflected a period of consolidation and adaptation from service-oriented strategic thinking towards conventionally oriented combined-arms warfare.
The 3G SAF (2000s onwards) has been viewed in terms of transitioning towards multi-mission-type forces with capabilities ranging from defence diplomacy to conventional warfare against a wide spectrum of threats.
In the process, the SAF's doctrinal orientation and operational conduct have also shifted significantly.
In the 1970s, the SAF adopted an island-defensive "poisoned-shrimp" strategy, which envisioned high-intensity urban combat imposing unacceptable human and material costs on potential aggressors.
In the 1980s, the SAF moved towards a "porcupine" strategy. This was aimed at limited-power projection in Singapore's near seas. It envisioned taking a pre-emptive stance by transferring a potential conflict beyond Singapore's territory.
Since the mid-2000s, the SAF has been developing what it terms a "dolphin" strategy - a "smart" or networked SAF leveraging not only precision firepower, manoeuvres and superior information, but also defence diplomacy in diverse military operations in geographically more distant areas.
In doing so, the SAF's gradual conceptual, organisational, technological and operational 3G transformation has continued to qualitatively outpace its neighbours' in relative terms.
Going forward, however, Singapore faces competing strategic narratives in terms of which types of adversaries and contingencies will prove most consequential in the future.
For example, the intensifying strategic competition in the South China Sea may restrict the SAF's freedom of action in potential future crises or even during peacetime operations. The SAF will have to learn to operate in contested environments characterised by the presence of sophisticated long-range precision strike assets such as ballistic missiles, submarines and fifth-generation stealth fighters.
At the same time, the SAF is facing non-linear threats ranging from terrorism to cyber and information warfare, coupled with increasing internal demographic and resource constraints.
The resulting hybrid security environment makes traditional defence planning strategies less effective.
Traditional planning procedures start with certain threat assessments. But when threats are unclear, planners need to hedge - by preparing for different possible futures, and developing a portfolio of capabilities that can prepare people for a range of contingencies. But hedging is very expensive, particularly with the increasing costs of advanced weapons technologies.
Amid conditions of strategic uncertainty, the 4G SAF will therefore need to focus on institutional agility - developing a set of capabilities to anticipate changing conditions in advance of need, while maintaining core operational readiness.
To do so, the SAF must build the next generation of competent and committed leaders of character who improve and thrive in ambiguity and chaos. This means investing in professional military education that shapes strategic culture embracing innovation in complex environments.
Historically, Singapore's strategic culture has paradoxically served both as an enabler and a constraint in the SAF's military modernisation.
On the one hand, the SAF has been able to assimilate new technologies and maintain high standards in training, readiness and professional ethos.
On the other hand, Singapore's strategic culture has precluded an environment supporting individual "mavericks" challenging the established norms through a bottom-up-type innovation, while discouraging failure.
The 4G SAF should therefore leverage Singaporeans with problem-focused, action-oriented, decision-making styles, while shifting its organisational ethos towards rewarding bottom-up initiative, creativity, assertiveness, practicality, simplification, adaptation, flexibility and tactical improvisation.
In short, the SAF has to nurture "institutional mavericks" capable of tackling entrenched barriers to military innovation.
As military-technological gaps in South-east Asia narrow, Singapore will also have to search for its niche military-technological innovations to create strategic advantages.
In this context, the SAF needs to focus more on mapping trajectories of strategic competition and military innovation in East Asia.
Comparative case studies of military innovation trajectories in different settings may help Singaporean policymakers to detect change in new approaches to combat, and prompt a debate of the validity of established strategic paradigms.
For example, the newly established SAF Defence Cyber Organisation should begin with developing operational knowledge and concepts in the context of military action in cyberspace.
Ultimately, the strategic effectiveness of the 4G SAF will depend on the direction and character of Singapore's defence diplomacy and strategic partnerships.
Strategic partnerships shape Singapore's external environment; prevent potential risks, dangers and threats; and, where it proves impossible to avoid them, provide timely and effective joint responses.
While relying on strategic partners may impose greater foreign policy constraints and external dependencies, this may be necessary for Singapore's defence, particularly in the context of countering potential multiple, cascading crises that characterise hybrid warfare.
• The writer is an assistant professor in the Military Transformations Programme at the Institute of Defence and Strategic Studies, based at the S. Rajaratnam School of International Studies, Nanyang Technological University.