I do not need to show proof since I am not asserting a positive
fact. You are, in effect, asking me to prove a negative, which
makes no sense. Now calm down and show me the relevant parts of the
constitution.
The relevent part of the statue states:
125. Whoever wages war against the government of any power in
alliance or at peace with the Government, or attempts to wage such
war, or abets the waging of such war, shall be punished with
imprisonment for life, to which fine may be added; or with
imprisonment for a term which may extend to 7 years, to which fine
may be added, or with fine.
You assert that the Singapore governemtn is at peace with
everyone and therefore, you cannot join a foreign army. That is
clearly wrong and besides the point; there is no direct ban on
joining a foreign army.
You seem to take a very simplistic view of the law: first what is
the definition of 'any power at peace with the government'? What is
considered a 'power'? What is 'waging war'?
I will point to another flaw in your assertion - If france sends
troops (including you) to afghanistan to hunt "terrorists", how can
it be said that you are waging war against a power at peace with
Singapore? That will clearly not be caught by the section. What if
france decides to invade malaysia but I am in afghanistan hunting
said terrorists? I think it would be difficult to show that you
have waged war against malaysia. Moreover. do you think france,
knowing of the law, is going to tell Singapore where you have
been?
You mention that there have been 'cases'. Again, prove it and stop
behaving like a bloody noob! You act as if this is the first time
you have had to prove an assertion!

Btw: You seem, in my approximation, to have defamed me -you said
that I have abetted an offence under the statute! -Gosh-! You are
forgiven and I shall not be pursuing legal action. But you really
ought to word your posts carefully.