U.S. President Donald Trump gestures during his visit to a section of the U.S.-Mexico border wall in Otay Mesa, California, U.S. September 18, 2019. Trump threatened to do “dastardly things” to Iran in response to the drone attacks on the world’s largest oil plant in Saudi Arabia. The US President indicated he is wary of involving America in another war in the Middle East – but he did not rule out a military attack. (Photo by Tom Brenner/Reuters)

A drone operated by paramilitary police flies over the site of last week's explosions at Binhai new district in Tianjin, China, August 17, 2015. Many operations have resumed at China's Tianjin port, trade sources said, after explosions last week that killed more than 100 people and disrupted business at what is an important oil, gas and bulk import harbor for Asia's biggest economy. The explosions on August 12 led to the disruption of all chemical and oil tanker discharges at the port, and imports of iron ore were also affected. (Photo by Kim Kyung-Hoon/Reuters)

A man takes a selfie in front of a fire from oil that has been set ablaze in the Qayyarah area, some 60 kilometres (35 miles) south of Mosul, on October 19, 2016, during an operation by Iraqi forces against Islamic State (IS) group jihadists to retake the main hub city. In the biggest Iraqi military operation in years, forces have retaken dozens of villages, mostly south and east of Mosul, and are planning multiple assaults for October 20. (Photo by Yasin Akgul/AFP Photo)

People crowd together in an attempt to buy chickens at a Mega-Mercal, a subsidized state-run street market, in Caracas January 24, 2015. President Nicolas Maduro shook up complex currency controls on Wednesday and also prepared Venezuelans for a rise in the world's cheapest fuel prices in response to a recession worsened by plunging oil revenue. The socialist-run OPEC member's economy shrank 2.8 percent in 2014 while inflation topped 64 percent, the socialist leader announced in a speech to parliament, in what is almost certainly the worst performance in Latin America. (Photo by Carlos Garcia Rawlins/Reuters)

Tao Xiangli gets out of his homemade submarine after operating it in a lake on the outskirts of Beijing September 3, 2009. Amateur inventor Tao, 34, made a fully functional submarine, which has a periscope, depth control tanks, electric motors, manometer, and two propellers, from old oil barrels and tools which he bought at a second-hand market. He took 2 years to invent and test the submarine which costs 30,000 yuan ($4,385). (Photo by Christina Hu/Reuters)

Nepalese Hindu devotees offer oil lamps in the Bagmati River as they observe the festival of Bala Chaturdashi in the early morning hours at the Pashupati Temple in Kathmandu, Nepal, 28 November 2016. Seven kinds of seeds – paddy, barley, sesame, wheat, gram, maize and finger millet – are sown around the temple premises in the name of loved ones departed during the last three years, in the belief that the departed souls will receive salvation. (Photo by Narendra Shrestha)

The Chilean ship “Skorpios II” is seen after it ran aground in “Maillen” island, near Puerto Montt, south of Santiago, in this handout picture from the Chilean Navy, February 5, 2015. According to the Chilean Navy, the ship's 89 passengers and 31 crew members were all evacuated and no oil spills or casualties were reported. (Photo by Reuters/Chilean Navy)

A soup for the students is pictured during an activity for the end of the school year at the Padre Jose Maria Velaz school in Caracas, Venezuela July 12, 2016. Due to the faltering socialist economy and the plunge in global oil prices, Venezuela has been in recession since early 2014. Due to the faltering socialist economy and the plunge in global oil prices, Venezuela has been in recession since early 2014. It suffers from the world's highest inflation and is experiencing shortages of basic goods, from milk to medicines. (Photo by Carlos Jasso/Reuters)