diff --git a/src/Symfony/Component/Validator/CHANGELOG.md b/src/Symfony/Component/Validator/CHANGELOG.md
index 70e4eb432f..c5ad6222ce 100644
--- a/src/Symfony/Component/Validator/CHANGELOG.md
+++ b/src/Symfony/Component/Validator/CHANGELOG.md
@@ -5,6 +5,7 @@ CHANGELOG
 -----
 
  * added the `Hostname` constraint and validator
+ * added option `alpha3` to `Country` constraint
 
 5.0.0
 -----
diff --git a/src/Symfony/Component/Validator/Constraints/Country.php b/src/Symfony/Component/Validator/Constraints/Country.php
index 1eaaa985fc..1cf099c64a 100644
--- a/src/Symfony/Component/Validator/Constraints/Country.php
+++ b/src/Symfony/Component/Validator/Constraints/Country.php
@@ -30,6 +30,7 @@ class Country extends Constraint
     ];
 
     public $message = 'This value is not a valid country.';
+    public $alpha3 = false;
 
     public function __construct($options = null)
     {
diff --git a/src/Symfony/Component/Validator/Constraints/CountryValidator.php b/src/Symfony/Component/Validator/Constraints/CountryValidator.php
index acb966b270..895cca3df1 100644
--- a/src/Symfony/Component/Validator/Constraints/CountryValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/CountryValidator.php
@@ -43,7 +43,7 @@ class CountryValidator extends ConstraintValidator
 
         $value = (string) $value;
 
-        if (!Countries::exists($value)) {
+        if ($constraint->alpha3 ? !Countries::alpha3CodeExists($value) : !Countries::exists($value)) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($value))
                 ->setCode(Country::NO_SUCH_COUNTRY_ERROR)
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/CountryValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/CountryValidatorTest.php
index 4f8ad86c5c..e46079838d 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/CountryValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/CountryValidatorTest.php
@@ -103,6 +103,55 @@ class CountryValidatorTest extends ConstraintValidatorTestCase
         ];
     }
 
+    /**
+     * @dataProvider getValidAlpha3Countries
+     */
+    public function testValidAlpha3Countries($country)
+    {
+        $this->validator->validate($country, new Country([
+            'alpha3' => true,
+        ]));
+
+        $this->assertNoViolation();
+    }
+
+    public function getValidAlpha3Countries()
+    {
+        return [
+            ['GBR'],
+            ['ATA'],
+            ['MYT'],
+        ];
+    }
+
+    /**
+     * @dataProvider getInvalidAlpha3Countries
+     */
+    public function testInvalidAlpha3Countries($country)
+    {
+        $constraint = new Country([
+            'alpha3' => true,
+            'message' => 'myMessage',
+        ]);
+
+        $this->validator->validate($country, $constraint);
+
+        $this->buildViolation('myMessage')
+            ->setParameter('{{ value }}', '"'.$country.'"')
+            ->setCode(Country::NO_SUCH_COUNTRY_ERROR)
+            ->assertRaised();
+    }
+
+    public function getInvalidAlpha3Countries()
+    {
+        return [
+            ['foobar'],
+            ['GB'],
+            ['ZZZ'],
+            ['zzz'],
+        ];
+    }
+
     public function testValidateUsingCountrySpecificLocale()
     {
         // in order to test with "en_GB"