Is the United States ready to defend Taiwan against an attack by China? What about Russian attempts to militarily subdue Ukraine? Will Washington limit its response to Moscow to sanctions and other nonmilitary measures?

When it comes to these geopolitical questions, no one should be ready to make any assumptions — that would add more destabilizing risk to a very delicate diplomatic situation.

For China and Russia, the two situations might not be too dissimilar. For Beijing, getting control over Taiwan would be a belated conclusion of the Chinese Civil War fought between 1927 and 1949. For the Kremlin, getting Ukraine and Belarus would effectively mean going back to the Czarist Greater Russia of the 19th century.

In both cases, neither country has made much of a secret of its intentions. Chinese President Xi Jinping returns repeatedly to his ambition to establish “one China” under the authority of Beijing.

This summer, Russian President Vladimir Putin published a remarkable essay in which he extensively justified his vision of a Greater Russia that would encompass both Ukraine and Belarus. Sometimes clouded in diplomatic jargon, he nevertheless made clear his view that the language in the Soviet constitution giving Ukraine and Belarus the right to independence was a profound mistake and that in his opinion their future could only be in some form of joint sovereignty under the ultimate authority of Moscow.

What Putin conveniently failed to mention is that the independence of Ukraine — as well as Belarus — is recognized by every other nation around the world. And there are no ambiguities as to its borders, which is why the United Nations General Assembly approved a resolution urging Russia to end its occupation of Crimea.

This in no way takes away the historical and cultural connections between nations that may have shared a common past and history. There are numerous examples of independent nations sharing deep cultural, linguistic, religious and other links with equally independent neighbors.

The United States is not committed to the defense of Taiwan by any treaty or other obligation under international law, but it’s difficult to avoid the impression that much of the American military planning for the years ahead is driven by the need to deter any Chinese military move against Taiwan.

Indeed, even President Joe Biden himself recently said the United States would defend Taiwan, although the White House was quick to make clear there was no change to the established policy of “strategic ambiguity.” Then what about Ukraine?

Here, the legal situation is crystal clear. Any aggression would give Ukraine the right under the U.N. Charter to ask for international help.

Right now, security assistance is already there, but Washington and key European allies should be more emphatic: They would help Ukraine defend itself in the face of any large-scale military aggression.

Any invasion should be met with more than sanctions. Putin is pushing the alliance — and though he can be reassured that Ukraine won’t become a NATO member anytime soon and there won’t be any permanent bases, aggression will be met with an unequivocal defense.

Putin has made his intentions clear. His revisionist view of Russia’s role in the region is largely opportunistic. But the United States and European allies, acting in concert with Ukraine, must deny him any opportunity.

There can be no room for misunderstanding. An attack against Ukraine would be as devastating to the European order as an attack on Taiwan would be to the Asian order.

There are diplomatic and peaceful ways to channel the will of different peoples — but there are no excuses for military powers forcing them to accept a new reality.