Shortest answer:
No.
- Uncertainty is so important in war that one cannot be sure of defeat either.
- Even if certainty could be imagined here (it cannot!), it is still hard to imagine how it may apply to a whole country, "both its people and its leadership". Only in a war or/and totalitarian propaganda discourse can a such statement be imagined.
- Propaganda can only be optimistic. If a such totalitarian unanimity could be achieved, or simply in order for it to be articulated in propaganda, the goal can only be victory, and not defeat.
Elaborating a bit more:
Defeat and victory are relative terms, depending on the goals, which in turn can be multiple and of different degree of probability. Certainty and uncertainty are decisive factors here. One could start a war that as such has no chance of winning but that might trigger further events (further wars, alliances) that they want to achieve.
Also the issue of "who started first" is a relative one too. Weaker countries may start wars because their position is untenable anyway (they suffer too much or are about to be conquered anyway).
Not all wars are total wars, and that of Japan against the US might have succeeded at least as far as reaching some intermediary goals. Unconditional surrender (as one comment says) was not a necessary scenario initially. Japan might have imagined some kind of a settled peace, just as the Nazis hoped for until very late. Japan wasn't sure it will lose the war, their goal was to destroy the US fleet, and that wasn't an impossible task in fact. They wanted their share of colonial empire (the Nazis too in fact, according to Timothy Snyder), and they could have hoped to have that confirmed in the end anyway on China's expense, like the Nazi's initially hoped to get one in Ukraine (if it wasn't for the stubbornness of the Brits and the Soviet peoples themselves). Japan and Germany wanted to be respected, that is be equal to the other colonial powers, and the war between such powers needn't be motivated by certainties. In the aristocratic imaginary of both imperialist Japanese and Nazi Germans war was the state of normality (like for a medieval knight or a samurai), and that didn't require certitude of victory. It entailed in a way the contrary, the certitude of (hopefully glorious) death: but not of defeat.
Arguably Japan is not a good example here, but from a general perspective one may say that many rebellions or wars of liberation against a much stronger power would qualify. Just like one may lose battles and win the war, or lose the war but win the peace, many intermediary cases are possible.
"Knowing" is also a relative term. What can it mean to "know" you will win? It can only mean "hope", thus fighting is never done "knowing" you'll lose no more than it is done knowing you'll win. - And what can it mean that the leadership knows something but not the people, or that both, or none, knows it? (How can we separate between what the Japanese generals knew and what the "people" did? Was "the people" even supposed to know they'll win or lose? And was a such popular knowledge supposed to count in the decision of starting the war? Isn't that just propaganda?) - Ignorance, like hope, is a big part of "knowing" such things.
From the perspective of yet unborn nation states or of otherwise oppressed peoples it is a big victory even to be able to mount an armed action against the masters (like Serbs, Greeks, Bulgarians against the Ottoman, the native Americans against the US, Algerians against the French, Indians against the British, Caucasus peoples against the Russian, other colonized peoples against the colonizers, Poles against the Russians or the Germans).
Starting a war may equate to proclaiming a new state (status, liberty), and for oppressed peoples that is as important as victory.
In the history of my native Wallachian and Moldavian lands, wars against the Turks had the goal sometimes to trigger an intervention from Hungary or Poland, or just press for the change in the conditions of the dependent status, but that doesn't mean they couldn't have at the same time the maximalist goal of removing that dependence. There are also cases were one could argue that these principalities periodically rebelling against the Turks contributed to their "victory" of not being fully occupied and keeping internal autonomy. — But the fact that success of these military actions was very relative, or that they ended mostly in failure (or "half-victories") might also have been a factor why the Ottoman felt that fully integrating them into the empire (like the other European provinces were) wasn't worth the effort.—
War and peace are also a matter of imagination and ethics. Sometimes the Mongols used to send emissaries before attacking, letting the recipient know that refusing Mongol demands equated to a declaration of war. Thus, it was the Hungarian or Polish kings that were made to appear as rejecting peace. But for these kings surrendering to the Mongols without a fight was ethically but also practically unimaginable. That was because they didn't knew who the Mongols were, but also because they didn't knew how to surrender without a fight! (Mongol brutality and cruelty was a political means of propaganda: of making people understand how one can and must surrender without a fight - the equivalent of the present atomic menace). Therefore they chose to fight the Mongol although the chances of beating them were slim (and although historians have concluded that their slim victories counted for little in the outcome of Mongols not occupying all Europe.)
