On the issue of US bases, Iraqi sovereignty and sanctions 1/
US military bases in Iraq were built during the GW Bush presidency. When the US pulled out of Iraq at end of 2011, whatever remained was considered Iraqi and already paid for. The US signed a Status of Forces Agreement (SoFA) in 2008 specifying this: mcclatchydc.com/news/nation-wo… 2/ 
SoFA expired on 31 Dec 2011. The US and Iraq also signed a Strategic Framework Agreement (SFA) in 2008 that is still in effect. It states the US will not retain bases or permanent military presence nor use Iraq to launch attacks against other countries: photos.state.gov/libraries/iraq… 3/
The US troops that are currently in Iraq are part of a request for assistance to combat ISIS that was sent in 2014. These troops are meant to advise, train and assist Iraqi troops. This request was sent by the Iraqi government and can be revoked at any time 4/
Iraq currently has a waiver on secondary sanctions being imposed on it by the US due to economic sanctions against nations that trade with Iran. That is set to expire next month and it is possible the US will not renew the waiver 5/
If US troops are expelled from Iraq and Trump does decide to apply new primary sanctions they would have huge economic implications for Iraq. Aside from military support Iraq also relies on fianancial assistance to the CTS and Peshmerga 6/
In summary, there are no US bases in Iraq (they co-locate and share Iraqi facilities), Iraq will not pay the US to remain or withdraw, the US may cut off financial assistance, sanctions are a possibility but unlikely for now 7/
