UK State Pension taxable or tax exempt

I am a US citizen and a UK citizen and permanent US resident. I receive a UK state pension which is similar to social security. Is this pension taxable or tax exempt in the US under the US-UK tax treaty article 17 or 18? If tax exempt, how do I report it on 1040 and/or form 8833? What internal revenue codes do I use on form 8833? Is form 8833 available on turbo tax or do I use the form from IRS website?