Can I deduct mileage and travel expenses for charitable organization for trips that go outside the united states?

Yes, you would deduct it the same way that you would any other travel costs for a charitable organization. 

Here is the TurboTax help content guidance for deducting charitable travel expenses:

Other Deductible Travel Expenses

These include:

 - Parking and toll fees
 - Air, rail, and bus transportation
 - Out-of-pocket expenses for your car
 - Taxi fares or other costs of transportation between the airport or station and your hotel
 - Lodging costs and meals

Travel expenses are deductible if they are directly related to the charitable service you're providing. However, you cannot deduct these expenses if there is a significant element of personal pleasure, recreation, or vacation involved in the travel. You must have substantial duties connected with the charitable organization while you're there.