About 30 per cent of the Government's total expenditure this year is being set aside to support defence, security and diplomacy efforts - spending that is "significant, but indispensable", said Finance Minister Heng Swee Keat.
And the Government will invest more, if the need arises, to protect Singapore's sovereignty and Singaporeans' well-being, he said.
"Everyone has a role to play to keep Singapore safe and secure. Let us continue to stay united in defending our home and way of life," added Mr Heng.
About $22.7 billion - or 28.3 per cent of the $80.3 billion total budgeted expenditure - is set aside for the Defence, Home Affairs and Foreign Affairs ministries this year.
The lion's share is for defence expenditure, which is expected to increase by 4.8 per cent to $15.5 billion. Spending for the other two areas is expected to be steady at $6.7 billion and $500 million, respectively.
Last year, about $21.9 billion - about 27.8 per cent of the $79 billion revised total expenditure - was allocated to the three ministries.
There was a greater focus on security and external relations issues in this year's Budget than in previous years, with Mr Heng speaking on these at the start of his speech.
Noting that a safe and secure Singapore "gives us the confidence to chart an independent course", he said the Republic cannot take its peace, prosperity and stability for granted, as it remains vulnerable to regional and global fluctuations.
Also, Singapore cannot waver in its commitment to defence and security - with diplomacy and deterrence as twin pillars of its approach - against an increasingly uncertain geopolitical environment.
Budget for the Defence, Home Affairs and Foreign Affairs ministries for FY2019.
Even as Singapore builds good relations with other countries through the Ministry of Foreign Affairs, the Singapore Armed Forces (SAF) lends weight to diplomatic efforts and ensures that negotiations with Singapore are taken seriously, noted Mr Heng.
"Should diplomacy fail, we must stand ready to safeguard our interests and defend ourselves," said Mr Heng, adding that Home Team agencies and the Cyber Security Agency of Singapore also ensure a safe and secure environment for all.
The SAF remains a "bulwark" as security threats evolve and become more complex, said Mr Heng.
He also cited how the threat of terrorism remains high, with Singapore continuing to detect individuals here who have been radicalised as it sees a global rise in attacks by radicalised individuals and cells.
In addition, the threat of malicious cyber activities is also growing, and connectivity can be exploited to disrupt and divide society through cyber attacks and the spread of falsehoods, Mr Heng said.
"In particular, foreign actors will try to influence our domestic affairs and politics. This is not new, but new technologies have made it easier for others to mount attacks with greater ease and intensity, and with more sophisticated tactics."
To stay ahead of these threats, Mr Heng said, Singapore must continue to innovate and build new capacities to meet security needs.
In the same vein, the Ministry of Home Affairs (MHA) will set up the Home Team Science and Technology Agency by this year to develop capabilities and support the ministry's operational needs.
"These capabilities will strengthen the Home Team's ability to carry out its mission of safeguarding Singapore," said Mr Heng, adding that more details will be given by the Home Affairs Minister.
MHA will also help the private security industry to innovate and use technology to better partner the Home Team, he said.
But every Singaporean needs to play a part too in keeping Singapore safe and secure, through the Total Defence approach, said Mr Heng.
At the national level, Singapore plans for the long term and takes measures such as stockpiling critical supplies, diversifying sources of water and strengthening food security.
Mr Heng's emphasis comes as Singapore and Malaysia are discussing several bilateral issues, which include disputes over maritime borders, airspace management and water prices.
Last December, Malaysia also announced it was considering limiting or stopping egg exports, and restricting exports of certain types of seafood.
Mr Heng added that as a people, Singaporeans must have the "psychological and emotional resilience to face crises stoically". "As threats get more sophisticated, Singaporeans must stay vigilant and guard against non-conventional forces that threaten to divide us."
Touching on the importance of national service and its role in forging a deep understanding that each Singaporean has a duty to defend the nation, he urged families and employers to support national servicemen in every way possible.
Meanwhile, Mr Heng noted that a sixth pillar of digital defence was just incorporated into Singapore's Total Defence framework. "Like other pillars of Total Defence, digital defence involves everyone - individuals, community groups, businesses and the Government," he said.
S. Rajaratnam School of International Studies research fellow Graham Ong-Webb said the increased focus on defence and security issues, despite the proportion of spending staying roughly the same this year, could be aimed at sending a message to other countries.
"It shows that we mean what we say and are willing to put that into resourcing to bolster diplomatic, defence and security lines to ensure that Singapore is not compromised in any way," he added.