The United States and its European allies vowed on Wednesday that Syrian regime head Bashar Assad will be held accountable for the sarin attack in the town of the rebel-held town of Khan Sheikhoun a year ago. "Today marks one year since the heinous attack... where Assads forces unleashed sarin nerve gas with tragic consequences for hundreds of men, women and children," said the foreign ministers of Britain, France, Germany and the United States in a joint statement. "We condemn the use of chemical weapons by anyone, anywhere," said foreign ministers Boris Johnson, Jean-Yves Le Drian and Heiko Maas and US Acting Secretary of State John Sullivan. "We are committed to ensuring that all those responsible are held to account. We will not rest in our efforts to seek justice for the victims of these abhorrent attacks in Syria." They also sternly criticized Russia for failing to strip its ally, Assad, of his deadly chemical arsenal. At around 7:00am on April 4, 2017, an air strike hit Khan Sheikhoun, a small town in northwestern Syria held by rebel fighters opposed to Assads Russian-backed regime. According to a UN-commissioned report, many residents of the town suffered the symptoms of an attack from an illegal nerve agent and more than 80 or them died, convulsed in agony. US President Donald Trump responded to the attack three days later, when US vessels in the Mediterranean fired 59 cruise missiles at a Syrian airbase. But Assad has denied ordering the attack and Russia has continued to give him diplomatic cover at the United Nations, despite having agreed to help remove his banned weapons. "In 2013, Russia promised to ensure Syria would abandon all of its chemical weapons," the ministers said. "Since then, international investigators mandated by the UN Security Council have found the Assad regime responsible for using poison gas in four separate attacks. "Instead of fulfilling its promise, Russia reacted by using its Security Council veto to shut down the investigation. "Each time a chemical weapon is used, it undermines the global consensus against their employment," they warned. "Any such use is a clear violation of the Chemical Weapons Convention and gravely undermines the rules-based international order." On his wedding anniversary on Wednesday, 29-year-old Syrian Abdulhamid Yusuf will have nothing to mark but a chemical attack that killed his wife and two baby children. "Ive been deprived of part of my body, of my soul," says the young widower, breaking into tears as he sits in the garden of his now empty home. An image of Yusuf holding the lifeless bodies of his 11-month-old twins -- Aya and Ahmad -- spread around the world in the wake of the attack. Yusuf also lost his wife Dalal and 16 other relatives, including his brother, nephew and many cousins. As Yusuf visits the cemetery to weed the graves of his loved ones twelve months on, his grief and anger is still raw. "I wont be able to start over. I wont forget the past," he says. "We want the international community to take a strong stand... Assad needs to pay", Yusuf says. Mohamed al-Jawhara, a 24-year-old with blond hair and blue eyes, lost his parents, nephew and several cousins. "It was such a shock. How do you bear seeing them all die in a single day?" Jawhara expresses frustration at what he sees as the insufficient response of the international community in holding Assad to account. "We hoped he would be tried and have to pay" for what he did, says the student, who aims to be a teacher one day. World leaders "have made statement after statement, but in the end they have been weak."