“Say what you mean, and mean what you say” is a dictum drilled into many of us at a young age. It is also one that US President Joe Biden has trouble keeping to. The latest example of his words having to be “reinterpreted” by his spokespeople was on Saturday, when Mr Biden concluded a speech in Warsaw by saying of Russian president Vladimir Putin: “For God’s sake, this man cannot remain in power.” The White House quickly issued a statement claiming that the sentence did not mean what everyone assumed it did. “The President’s point was that Putin cannot be allowed to exercise power over his neighbours or the region. He was not discussing Putin’s power in Russia, or regime change,” it said. This is becoming a pattern with Mr Biden. A day earlier he suggested to an audience of American armed forces that they would be going to Ukraine. This prompted another clarification from a White House spokesman: “The president has been clear we are not sending US troops to Ukraine.” He has contradicted his own team as to whether sanctions have a deterrent effect or not, and has answered both no and yes when asked if he would call Mr Putin a war criminal. Mr Biden’s press secretary Jen Psaki calls this her boss “speaking from his heart”. Others have less charitable explanations. Either way, the current occupant of the Oval Office has a history of saying things that have to be – let’s be plain about this – corrected afterwards. Last August he put Taiwan in the same category as Nato members and US treaty allies Japan and South Korea, and said that if “anyone were to invade or take action against” any of them, “we would respond”. This was quite the bombshell. Was Mr Biden suddenly upending the US’s long-standing, carefully calibrated stance and offering Taiwan, which Beijing regards as a renegade province and is not an American treaty ally, an explicit defence guarantee? No. Yet again, an administration official had to spell out that policy towards the island had not actually changed. These “gaffes” are not to be taken lightly. For even when they are “clarified” afterwards, the actual words cannot be taken back. They can and will be used by others who will take them at face value, possibly for their own purposes. On the other hand, maybe these slips of the tongue are a reflection of Mr Biden’s true feelings. Perhaps he is preparing for war over Taiwan, or asking the CIA for plans to create instability in Moscow. Who knows? Such uncertainty is extremely dangerous in the tense geopolitics of today’s world, and when leaders of powerful countries make statements that they do not, when it comes to it, really mean, it can lead to instability. Take former US president Barack Obama’s “red line” on the use of chemical weapons in Syria. They were used, but the red line was not enforced. How seriously, asked the rest of the world, should we take an ultimatum from America after that? This is not a call for a global security architecture based on red lines, swiftly implemented with lethal efficiency: this is a call for clarity. In East Asia, for instance, what was clear until relatively recently was that the US policy towards Taiwan was one of “strategic ambiguity”. America helps the island with its defence capacity but has no formal commitment to come to its aid, and officially “acknowledges” the Chinese position that the island is part of China. This has served everyone pretty well for decades. Many analysts believe that calls for the US to move towards supporting independence for Taiwan are reckless, and would only increase, not decrease the risk of confrontation. But so loud and prominent are these voices that we can no longer be certain that “strategic ambiguity” is still the US’s settled position. To stay in the region, a few years ago I asked a senior State Department official what red lines the US had in the heavily contested South China Sea. They didn't have any, was the answer. This may have seemed unsatisfactory to some, but it was in tune with former US Defence Secretary Donald Rumsfeld's “known unknowns” – at least we were clear what we couldn’t be certain about. The advantage of that was that it provided room for all parties to manoeuvre, and for possible creative compromises that have not yet been raised, and no one could accuse the US of failing to back promises that it had not made. To go back to Ukraine, western leaders who insisted that the country must be free to have a path to Nato membership were also guilty of saying something they didn't truly mean. It is ironic that Ukraine’s president Volodymyr Zelenskyy has now said repeatedly that neutrality is something he's willing to discuss. If there had been prior clarity on this – and there might have been if Mr Zelenskyy hadn't been led down the garden path by the West – this could have been a factor that maybe, just maybe, might have helped avoid war. Mr Biden is an affable chap with a generous heart and genuine empathy, whose verbal missteps have sometimes been comical. If you want a good laugh, look up video of the occasion during the 2008 US presidential campaign when he introduced Mr Obama as “Barack America”. But there is nothing funny about his all-too-frequent misstatements about American foreign policy. Words have consequences. “Loose lips sink ships”, as the Second World War slogan put it. At a time when a third global conflagration is no longer unthinkable, clarity from leaders could not be more crucial. Any of us could be on the ships that would be sunk or in the cities reduced to ashes if muddled announcements led to unstoppable escalation.