Today in Pictures: May 23

Boris Johnson MP views classic sports cars during a visit to Ginetta Cars Ltd during the Brexit Battle Bus tour in Yorkshire in Leeds, England. Johnson and the Vote Leave campaign are touring the UK hoping to persuade voters to back leaving the European Union in the Referendum on June 23.

Britain's Andy Murray reacts after winning a game in the third set, as he plays Radek Stepanek of the Czech Republic during their first round match of the French Open tennis tournament at the Roland Garros stadium in Paris.

Dustin Brown of Germany plays Dudi Sela of Israel during their men's single first round match at the French Open tennis tournament at Roland Garros in Paris.

President Barack Obama walks with chairwoman of the National Assembly Nguyen Thi Kim Ngan on the Presidential Palace compound in Hanoi, Vietnam. Second from right is National Security Advisor Susan Rice. President Obama started his first visit to Vietnam on Monday looking to bolster the government with trade opportunities and the possible lifting of an arms export embargo even as he pushes for better human rights from the one-party state.

Kenyan police charge as they engage in running battles between police firing tear gas and protesters throwing rocks, in the Kibera slum of Nairobi, Kenya. Kenya's police shot, beat and tear gassed opposition demonstrators across the country who tried to gather to call for the electoral commission to be dissolved due to allegations of bias and corruption.

President Barack Obama greets women at the door as he walks from the Bun Cha Huong Lien restaurant after having dinner with American Chef Anthony Bourdain in Hanoi, Vietnam.

A volunteer stands at the entrance of the 5000 Poppies Garden at the Chelsea Flower Show in London. The garden, created by Australians Lynn Berry and Margaret Knight is a tribute to their fathers who both fought in WWII.

Iraqi pro-government forces advance towards the city of Fallujah as part of a major assault to retake the city from Islamic State group.

A young boy uses a plastic bag to protect himself from a dust storm in New Delhi, India.