The steps taken by the Obama administration to relax parts of the long-standing trade embargo on Cuba, coupled with the visit there by the Congressional Black Caucus will reopen the old debate about Cuba policy.

Critics have long argued that the U.S.'s isolation of Cuba should be ended because it simply hasn't worked. After all these years Cuba remains as communist and repressive as ever. Better, they say, to engage Cuba and try to change her that way. This argument has particular appeal on the American left, where there is some admiration for Cuba, for its public health programs for example.

But the left did not like the Reagan policy of engagement with South Africa toward the end of its racist apartheid era. Liberals much preferred the isolation and economic sanctions which came later and which they believe forced South Africa to change its ways. So it is not easy to draw either clear ideological lines or clear lessons from these two cases.

What does seem clear is that the Obama administration is headed down the road of diplomatic engagement with Cuba, with Iran, and possibly North Korea as well. If it is fair to ask why not change a policy toward Cuba that has not worked, it seems equally fair to ask when was the last time engagement with a rogue regime like Iran or North Korea worked either.

Such questions suggest why Richard Nixon once said that the hard part of being president is not doing the right thing, but knowing the right thing.

With more than 35 years of journalism experience to draw from, Brit Hume currently serves as a senior political analyst for FOX News Channel (FNC) and contributes to all major political coverage. Hume also is regular panelist on FOX's weekly public affairs program, "FOX News Sunday" on Sundays at 2 p.m. and 6 p.m. ET. Click here for more information on Brit Hume