It has become a truism in discussions of Russia's takeover of Crimea that in the post-World-War-II international order, countries no longer rewrite borders through force — or if they do, they rarely find themselves faced with determined opposition from other states. As Secretary of State John Kerry put it, the Crimea campaign is a "19th-century act."

Such statements ignore major pieces of inconvenient history. Indeed, the late 20th century saw countries gobble up foreign territory. Even the more modest claim that such territorial conquest is unknown in Europe is not true. Sometimes these actions met determined international opposition, but just as often, they did not. Immediate objections fade. Indeed, a comprehensive study of post-World-War-II conquest finds that United Nations condemnation happens in well under half of the cases.

Russian President Vladimir Putin needed to look no further than his Black Sea neighbor Turkey for inspiration. In 1974, Turkey invaded northern Cyprus, and it continues to occupy the northern third of the island under an unrecognized puppet regime. Cyprus, a member of the European Union, is not a member of NATO. This has not prevented the development of close relations, and even solicitude, between the E.U. and its own occupier.

As Turkey was grabbing Cyprus, Morocco snatched the massive and resource-rich Western Sahara in a swift action, without firing a shot. The Moroccan invasion was met with a U.N. Security Council condemnation, which Rabat shrugged off. Although no nation has recognized Moroccan sovereignty over the occupied area, Morocco remains a close ally of the United States and the E.U. Indeed, U.S. policy now supports Moroccan proposals to retain the occupied territory under Moroccan sovereignty with local autonomy. Moreover, European companies happily help Morocco exploit the Western Sahara's resources, and recent treaties with Europe even acknowledge and engage with Moroccan control.

Perhaps the most egregious examples are the bloody conquests of entire countries. It seems 1975 was the year for such things, with North Vietnam wiping South Vietnam off the map and Indonesia seizing East Timor. All nations now recognize Hanoi's sovereignty over all of Vietnam. And despite a hostile Security Council resolution, the West quietly supported Indonesia's Timor position for decades, before Jakarta's brutality made the issue difficult to ignore.

More recently, Armenia successfully conquered parts of Azerbaijan in the 1990s, a move condemned by the E.U., which now seems unlikely to be reversed. And, of course, Russia snagged parts of Georgia just five years ago — and, after a series of Western threats, was punished with an Olympic Games.

When conquest fails, it is because of resistance from the target state — as with Argentina's bid for the Falklands, Libya's for parts of Chad and Iraq's attack on Iran. But international tsk-tsking does not do the trick. Saddam Hussein's invasion of Kuwait, which led to an international effort to eject him, is not the paradigm; rather, it's the exception.

Even in cases in which the conqueror's control remains in dispute, it does not poison international relations. Israel's 1967 Six-Day War successes are the exception that prove the rule: It is unimaginable that 45 years from now, the E.U. will be demanding that Russian exports be clearly marked to indicate that they did not come from "occupied Ukrainian territory." Based on the current threats of sanctions, it will not be doing this 45 days from now.

Indeed, the vigor with which the international community has maintained — and increased — its objections over Israel's presence in the West Bank may divert attention from other conquests. Putin knows this. Remarkably, Russia retained its status as a member of the "quartet" — with the United States, E.U. and U.N. — seeking to broker Israeli territorial withdrawals even after it invaded Georgia.

To be sure, the post-Cold-War world has seen an apparent reduction in territorial expansionism. This is not because of any fundamental shift in international mores, but for more mundane reasons. The wars of the 21st century have been wars of secession and dissolution. Separatism is a counterbalance to aggrandizement.

More important, territorial control has, on the whole, become less valuable for states. A much smaller percentage of today's value production comes from land and natural sources, so control of territory gets the occupier less. Moreover, improvements in communication and transportation make it much easier to have a docile puppet state.

Today, conquest is less often a national interest. But when it is, legal barriers pose little restraint. Indeed, the West's continued willingness to effectively abide the major land grabs of Turkey and Morocco suggests that, except for unusual cases, the West will do little to stop such acts in the future.

Eugene Kontorovich is a professor at Northwestern University School of Law who specializes in international and constitutional law. He wrote this article for the Los Angeles Times.