The United States will strengthen its military presence in Syria to prevent Daesh (the so-called IS) fighters from accessing oil fields and revenue, US Secretary of Defense Mark Esper said on Friday, the latest twist in President Donald Trump's policy on Syria. Trump has been softening his pullout plans for Syria after a backlash from Congress, including among key Republicans, who say he enabled a long-threatened Turkish incursion against Kurdish forces in Syria who had been America's top allies in the battle against Daesh. "We are now taking some actions... to strengthen our position at Deir el zor, to ensure that we can deny ISIS access to the oil fields," Esper told reporters during a press conference, using an acronym for Daesh. "We are reinforcing that position, it will include some mechanized forces," Esper said. Mechanized forces usually include tanks and other military assets. He did not say how many forces were currently in the region or how many additional forces would be sent. Any significant US military presence on the ground would need to be properly defended from potential attack, particularly in oil-rich areas of Syria that could become targets of not just Daesh militants but potentially Russian-backed or Iran-backed forces operating in the country. The vacuum left by Trump's partial withdrawal has created an opening that Russia exploited by moving forces into the area. US officials worry that Iran-backed forces in Syria could also capitalize on the chaos. Around 300 more Russian military police have arrived in Syria, the Russian defense ministry said on Friday, under an accord between Ankara and Moscow which halted Turkey's military incursion into northeast Syria. Amid fears that Islamic State could stage a comeback, Trump said on Wednesday a small number of US troops would remain in the area of Syria "where they have the oil," a reference to oilfields in the Kurdish-controlled region. Esper said his Turkish counterpart had told him that Ankara had recaptured some of 100 Daesh militants who are believed to have escaped from prison in Syria as a result of the Turkish incursion. Esper met Turkish Defense Minister Hulusi Akar on Friday in Brussels. — Reuters