after 9/11. and when you think about the counterterrorism response, philippa, that was launched here, it's really extraordinary. we are also seeing the speaker of the house of representatives, nancy pelosi. we are also seeing chuck schumer there, the senate majority leader. and of course, these are such politically polarised times at this moment, president biden is trying to take us back to those moments of unity after 9/11, saying that unity is america's greatest strength. and this is a day when the whole country is remembering those shocking events which change so many things in america, from the rather banal, like airport security, to the bigger picture, to the war on terror, that war lodged in afghanistan because the taliban were harbouring al-qaeda. but 20 years on, this moment 20 years ago, those planes were heading towards the world trade