Today is Cpl. Gilad Schalit's 21st birthday, his second in captivity. Schalit's family has organized a public rally in Tel Aviv's Kikar Rabin to mark the event, with a large birthday cake in the middle of the square. Organizers are expected to hand out balloons and magnets proclaiming that "Indifference can kill." Although three groups claimed responsibility for Schalit's abduction on June 25, 2006, it appears that he is being held in Gaza by the Hamas military wing. The other two groups, the Popular Resistance Committees and Army of Islam, follow Hamas's orders. Hamas knew exactly what it was doing when it released an audiotape from Schalit on June 25, the first anniversary of the kidnapping. The kidnappers had Schalit say that he was being treated well but needed medical attention, thereby allowing Hamas to dictate the headlines that appeared across the world that day. Similarly, Hamas's exiled leader, Khaled Mashaal, must have known Schalit's birthday was coming up when he told CNN on Friday that Schalit was alive, in good health and being treated in a "humanitarian way." Interviewed in a safe house in Damascus, Mashaal blamed Israel for not even considering Hamas's list of 350 Palestinian prisoners it wants released in return for Schalit's freedom. Yesterday it was the turn of Ahmed Youssef, an aide to Hamas's "prime minister," Ismail Haniyeh, who said in an interview with Israel Radio that if Israel freed Palestinian women and children from jail (he didn't say how many), Hamas might release a videotape of Schalit revealing his current condition as "a gesture of goodwill." What is Hamas's game? Its specific message over Schalit is that its demands will have to be met if Israel is ever going to secure his release. But its wider point is that nobody should delude themselves that it can be ignored when negotiations on the Israeli-Palestinian track are in the offing. It remains avowedly committed to a spoiler role at the first hint of progress. It is, therefore, anything but coincidental that the point is being pressed home on the eve of another summit between Prime Minister Ehud Olmert and Palestinian Authority Chairman Mahmoud Abbas. The two leaders are said to be discussing a new declaration of principles to be presented at a Middle East meeting in the fall called by US President George W. Bush. The Israeli government has been adamant that it will not deal with Hamas unless it recognizes our right to exist, renounces terrorism and agrees to abide by previous agreements. Israel has also made plain that it would not deal with the Palestinian Authority if the PA were to reconstitute its former unity government partnership with Hamas, as many in Fatah are urging Abbas to do. But the Israeli government is also coming under a degree of pressure to acknowledge Hamas's growing weight and power and engage with it. Such interaction, it is suggested, is not just the only way to secure the release of Schalit, but also the only pragmatic means of grappling with a new reality of Hamas prominence. But interaction now with an unreformed Hamas represents capitulation to terrorism, and can only further reduce any small likelihood of the Islamic group ever opting for reform. Meanwhile, it would discredit and further weaken the faint voices of genuine Palestinian moderation. The way forward, by contrast, requires Olmert and Abbas to reaffirm a partnership whose earliest concrete stages must involve concerted PA action to publicly oppose and practically counter acts of terrorism - including rocket attacks, bombings and kidnappings such as the one to which Schalit fell victim. Rather than exulting in the belief that, sooner or later, directly or via a third party, Israel will come crawling to its door, imploring it to release Schalit in an exchange deal, Hamas needs to be made to feel that Schalit is a liability who must be let go. The continued captivity of Schalit is an outrage. Abbas, who has garnered Israeli and international backing as the exemplar of moderation, can use today's meeting as a platform to demand Schalit's release, to condemn Hamas for holding him and to underline the damage caused to Palestinian interests by the ongoing acts of terrorism, including Schalit's imprisonment, carried out or fostered by Hamas. If followed by long-required action against terrorism that would improve security for both Israelis and Palestinians and begin to enable a return to substantive dialogue, this would be a fine birthday present for Schalit and, it is to be hoped, the beginning of a speedy process leading to his release.