Does income and mortgage interest on UK real estate count on income taxes for a US citizen living in the US?

I just moved back to the US after being in the UK for 10 years. I still own a home in the UK which is now being rented out. I just bought a home in the US, so now have two mortgages. (This was NOT the original plan) I have some dollars that I'd like to pay down some of this debt, but I'm not sure which mortgage is best to reduce. Is my rental income in the UK going to be taxable in the US (or UK?). Likewise, is the UK mortgage interest deductible in the US? Where should I put my extra funds?