EU chiefs on Tuesday pledged millions of euros of financial assistance to Greece to help tackle the migration surge from neighboring Turkey, warning against those wishing to “test Europe’s unity”.

Flying by helicopter over the Greek-Turkish border, where thousands of desperate asylum-seekers have tried to break through for days, European Commission President Ursula von der Leyen said the bloc would provide Greece “all the support needed”.

“Those who seek to test Europe’s unity will be disappointed,” von der Leyen said, standing alongside Greek Prime Minister Kyriakos Mitsotakis and the chiefs of the European Council and European Parliament.

“We will hold the line and our unity will prevail.”

The European Commission president said the bloc would provide 700 million euros ($777 million), half of it immediately, to help manage the migrant situation.

In addition, the EU border agency Frontex will deploy a rapid intervention team including an additional 100 guards backed by coastal patrol vessels, helicopters and vehicles, she said.

“Our first priority is making sure that order is maintained at the Greek external border, which is also the European border,” von der Leyen told journalists.

“I am fully committed to mobilizing all the necessary operational support to the Greek authorities,” she said, adding that Greece was acting as a “shield” for Europe.

Over 500 Frontex guards are currently deployed along Greek borders and Greece could also receive assistance in medical teams, mobile shelters, tents and blankets, she said.