2015, Iran and other world powers agreed to trade sanctions relief for explicit constraints on Iran's contentious nuclear program, including allowing the inspections of nuclear facilities by the International Atomic Energy Agency (IAEA). On 16 January 2016 the IAEA confirmed that Iran had complied with the agreement (the JCPOA), allowing the United Nations to lift sanctions immediately. However, on 8 May 2018, United States President Donald Trump announced the United States was withdrawing from the deal. On 7 July 2017, the United Nations passed the Treaty on the Prohibition of Nuclear Weapons, the first legally binding international agreement to comprehensively prohibit nuclear weapons, with the goal of leading towards their total elimination. It has been signed by 58 nations. Throughout the decade, North Korea expanded its nuclear capabilities, performing alleged nuclear tests in 2013 and 2016, which governments responded by placing international sanctions on the country. In response North Korea has threatened the United States, South Korea and Japan with pre-emptive nuclear strikes. However, in 2018, North Korea suggested that they may disarm their nuclear arsenal after negotiations with the United States. On 1 February 2019, The US formally suspended the Russo-American Intermediate-Range Nuclear Forces Treaty (INF), and Russia did the same on the following day in response. The US formally withdrew from the treaty on 2 August 2019. The United States initiated a renovation of its nuclear weapon arsenal. Terrorist attacks The most prominent terrorist attacks committed against civilian populations during the decade include, but are not limited to: Political trends International relations China was increasingly called a superpower in the early 2010s, including at the 2011 meeting between President Hu Jintao and United States President Barack Obama. China overtook the U.S. as the world's largest trading nation, filing the most patents, expanding its military, landing its lunar rover Yutu on the moon (ending a four-decade lack of lunar exploration) and creating China's Oriental Movie Metropolis as a major film and cultural centre. In 2018, global military spending reached the highest it has been since 1988, late Cold War levels, largely fuelled by increased defence spending by China and the United States, whose budgets together accounted for half of the world's total military spending. In 2019, the Lowy Institute Asia Power Index, which measures the projections of power in the Indo-Pacific, called both China and the United States the superpowers of the 21st century, citing immense influence in almost