United States President Donald Trump on Sunday (September 21) again invoked the Bagram air base in Afghanistan, saying in a Truth Social post that “If Afghanistan doesn’t give Bagram Airbase back to those that built it, the United States of America, BAD THINGS ARE GOING TO HAPPEN!!!”Trump earlier referred to Bagram during his recent visit to the United Kingdom, and in May and March this year. This time, Zakir Jalaly, an official at the Taliban Foreign Ministry, said, “The Afghans have not accepted a military presence in history, and this possibility was completely rejected during the Doha talks and agreement (before the Taliban seized power in 2021), but the door is open for further interaction.” The US and Afghanistan currently do not have diplomatic relations.Here is what to know about the site’s history, the US role in it, and the value Trump sees in it now.1. Who established the Bagram air base?The largest air base in Afghanistan, Bagram, lies some 60 km to the north of Kabul, in the strategic Parwan province.Experts say that in Parwan lie the keys to controlling much of Afghanistan due to its linkages to key cities, including Kabul, Kandahar and Bamiyan. The air base was originally built by the Soviets in the 1950s, when both the US and the USSR were jockeying for influence in Afghanistan. This earlier explainer details that history.During the Soviet-Afghan War from 1979-89, Bagram became a vital Soviet base against the mujahideens. After the Soviet withdrawal in the 1990s, the abandoned Bagram base became a frontline in a war between the Taliban and the Northern Alliance fighters.2. When did the US forces control Bagram?After September 11, 2001, the US and its allies took over, as they toppled the Taliban regime. Over the next two decades, as the “War on Terror” raged on, Bagram became the epicentre of the American presence in Afghanistan.Story continues below this adThe base was expanded to over 77 sq km and a new, improved runway was constructed, as were medical facilities and fast food joints for US personnel. A disused hangar was used as a detention facility, and drew comparisons to the Guantanamo Bay base in Cuba due to reports of torture and abuse by US soldiers.The first Trump administration (2017-21) in 2020 signed a deal with the Taliban, which provided for a pullout of all NATO troops from Afghanistan soil after two decades. Over the next year, the Taliban gained ground. The final American aircraft took off from the Kabul airport on August 30, 2021. US forces had vacated Bagram on July 2; the base fell to the Taliban on August 15.With little domestic support for keeping troops in Afghanistan, keeping the Bagram Airfield was never on the cards. “Retaining Bagram would have required putting as many as 5,000 US troops in harm’s way just to operate and defend it,” then Defence Secretary Lloyd Austin told the House Armed Services Committee in September 2021.3. What is Trump’s rationale for controlling Bagram?The base is under Taliban control today. That said, the US has long been concerned about China making inroads into Afghanistan after its exit. Trump, however, has made a range of claims on the issue. He said earlier this year that Bagram is “an hour away from where China makes its nuclear weapons”, but “they (presumably the Joe Biden administration) gave Bagram up”.Story continues below this adIt is unclear which Chinese nuclear facility Trump was referring to. The closest known testing site is 2,000 km away at Lop Nur in Xinjiang, where China tested its first atomic bomb in 1964. The closest nuclear weapons facility is the Koko Nur complex, further east in the Qinghai province.When Trump made similar comments in March, the Taliban had issued a strong denial. “Bagram is controlled by the Islamic Emirate (Taliban), not China. Chinese troops are not present here, nor do we have any such pact with any country,” it had said.That is not to say that Afghanistan is not on China’s radar. Even as most countries have been wary of fully engaging with the Taliban, China gave the Taliban representative in Beijing ambassador credentials last year.For China, relations with Afghanistan matter because it has a sizable Muslim population of its own in the bordering Xinjiang. Beijing would want to ensure that radical elements in Afghanistan do not cross over into its own territory. To that end, it has attempted to bolster ties within a limited framework and also made some investments in Afghanistan.Story continues below this adFollowing Trump’s latest comments, a Chinese Foreign Ministry spokesperson stated that they respect Afghanistan’s sovereignty and support the country in making decisions about its future. “Hyping up tensions and creating confrontation in the region runs counter to the people’s aspirations,” the statement added.