of President Mohammad Khatami (in office 1997–2005), the government paid special attention to developing the country's oil and gas industry. Oil was defined as inter-generational capital and an indispensable foundation of economic development. Thus, between 1997 and 2004 Iran invested more than US$40 billion in expanding the capacity of existing oil fields and discovering and exploring new fields and deposits. These projects were financed either in the form of joint investments with foreign companies or domestic contractors or through direct investment by the NIOC. In accordance with the law, foreign investment in oil discovery was possible only in the form of buyback agreements under which the NIOC was required to reimburse expenses and retain complete ownership of an oil field. Marketing of crude oil to potential buyers was managed by the NIOC and by a government enterprise called Nicoo. Nicoo marketed Iranian oil to Africa, and the NIOC marketed to Asia and Europe. According to IHS CERA estimate, oil revenue of Iran will increase by a third to USD 100 billion in 2011 even though the country is under an extended period of U.S. sanctions. Post-JCPOA era The signing of the JCPOA in July 2015 by Hassan Rouhani and Javad Zarif with Barack Obama heralded a new era of détente in foreign relations. With it, Iran was allowed to come in from the cold, as it were and once again to sell its oil unencumbered on the world stage. The withdrawal by Donald Trump from the JCPOA in May 2018 was an ill wind for Iran because he decided to re-apply the sanctions regime that had caused such difficulties to Khamenei. For example, the Grace 1 oil tanker was captured near Gibraltar in July 2019 at the request of the US by the armed forces of the UK. The incident was one of several that have been labelled as the 2019 Persian Gulf crisis, but the crisis soon widened to encompass more distant seas where Iranian arms are impotent. In May the Iranian tanker Happiness 1 suffered difficulties near Jiddah. In August the tanker Helm encountered difficulties while transiting the Red Sea, and in October the Iranian tanker Sabiti was attacked by two missiles of unknown origin, again in the Red Sea. The fully laden Sabiti had been destined for the "Eastern Mediterranean". China is a significant supporter of the Iranian petroleum industry. In 2017, 64% of an export total