[jQuery] (validate) conditional statements in .validate

[jckos]

Hi,

I would like to make fields required based on a country selection in a
drop down.  I tried a few variations of the following but can't get it
to work.  Is there another way of going about this?

$("#country").change(function(){
                var ctry= $("#country").val();
         if ( country == "United States"){
        $("#checkoutGuestDynForm").validate({
      rules: {
              state: "required",
              zipCode: {
                        required:true,
                        maxlength:  10,
                        minlength: 5
                          },
        phone:"required" {
        });
         }
        else if (country == "Canada"){
        $("#checkoutGuestDynForm").validate({
          rules: {
                  province: "required",
                   postalCode: "required",
                  phone:"required"}
         });
        }
        else (country == "Intl"){
        $("#checkoutGuestDynForm").validate({
                 rules: {
                    stateIntl: "required",
                    zipCodeIntl: "required",
                     phoneIntl:"required"
                         }
                  });
               }
        });