The escalating situation along the Greek border has again made headline news of how the European Union is going to deal with large number of migrants seeking access to the continent.

Around 13,000 refugees have gathered at the Greek-Turkish border demanding access to the EU, since Turkey announced it was opening its doors to the neighboring country. Greece plans to stop the migrant flow into the EU bloc and has demanded the intervention of Frontex, the EU border force.

But what role does Frontex play in patrolling the EU's external borders?

What is Frontex?

Frontex (from the French Frontières extérieures, which means external borders) was created in 2004 and started its activities in 2005 as the European Agency for the Management of Operational Cooperation at the External Borders. Also in 2004, Poland joined the EU, so it was decided to locate the new agency's headquarters in its capital, Warsaw.

Frontex's mission is to "ensure safe and well-functioning external borders," making sure that the free circulation of EU citizens within the Schengen area is counterbalanced by a tight migration control at its borders with neighboring countries outside the EU.

During the migrant crisis of 2015-16 in Europe, Frontex was found to have very limited powers of intervention, insufficient to support the pressure EU member states were facing at their external borders. In 2016, its mandate was strengthened and its name changed to the European Border and Coast Guard Agency.

What does it do?

The main function of Frontex is to coordinate action, with the authority of EU member states, to exercise control at their external borders.

Frontex monitors the situation at the EU's external borders, helps to share information on migratory patterns and activities among member states and provides training for border guards across Europe.

Under the 2016 mandate, Frontex assists EU member states in "forced returns of people who have exhausted all legal avenues to legitimize their stay within the EU" and can organize return operations "on its own initiative."

It also has permission to operate on non-EU territory, as long as it borders at least one EU member state, in case of migratory pressure. And it can organize joint operations and rapid border intervention to assist an EU member state in an emergency situation, creating a "rapid reaction pool."

This involves the deployment of at least 1,500 border guards and other relevant staff, to be provided by member states upon request by Frontex.

Who's in charge of it?

The agency is managed by an executive director – since 2015 that's Fabrice Leggeri, who previously worked for the European Commission – appointed by a management board. This is composed of representatives of the heads of the border authorities of the 26 EU Schengen member states, plus two members of the EU Commission, who meet five times a year.

The management board establishes the agency's annual budget. Once endorsed by the management board, the budget is presented to the European Commission and must be approved by the European Parliament.

Frontex's budget has grown from an initial $6.7 million in 2005 to $358 million in 2018.

As part of the agency's future expansion plans, it aims to increase its budget to $10 billion, distributed between 2021-27, to support an increase in staff to 10,000 border and coastguard officers by 2027.

Frontex must also report to the European Parliament all its activities and expenses.

What has Frontex done so far?

Frontex's main operations at the moment are in Italy, Greece, Spain, and the Western Balkans.

Frontex started Operation Triton in Italy in 2014, after the Italian Operation Mare Nostrum – aimed at rescuing the thousands of migrants trying to reach the country via the Mediterranean – proved too costly. It focuses on border control and search and rescue operations. Fifteen countries assisted Italy, contributing two aircraft, three ships and seven teams of specialized staff.

Operation Triton was replaced in 2018 by Operation Themis, which extended its area of intervention to the migratory routes from Algeria, Tunisia, Libya, Egypt, Turkey and Albania.

Frontex has been active in Greece since 2006 with Operation Poseidon, covering the Greek sea borders with Turkey and the Greek islands. Operation Poseidon was strengthened in 2015 with additional vessels, aircraft and officers to support Greece in patrolling and search and rescue operations.

In Spain, Operations Hera, Indalo and Minerva ensure border control on the route between Morocco and Spain, with more than 180 officers deployed.

Frontex also deploys officers in Hungary and Croatia to assist the national authorities in fighting cross-border criminal activities, including detecting forged documents, stolen cars, illegal drugs and weapons.

The agency has been previously accused of misconduct for human rights violations and breaching international refugee conventions.

Who controls the operations?

An operation normally starts when an EU member state requests an intervention from Frontex. The agency can also initiate an operation after a vulnerability assessment.

All officers deployed by Frontex work under the command of the authorities of the country where the intervention is taking place, with at least one officer from the host country present aboard every vessel, aircraft or patrol car.

What will it do in Greece?

Greece has requested a rapid border intervention to ease the pressure on its border with Turkey, and the request was approved by Frontex on Tuesday 3 March.

A rapid intervention request must be assessed by a group of experts and a decision must be taken by Frontex's executive director within two days of receiving the request.

An operation plan is then drawn up by Frontex's management board and the interested member state within three days from approval, then officers are deployed within five days from the approval of the plan and equipment within 10 days.

"Given the quickly developing situation at the Greek external borders with Turkey, my decision is to accept to launch the rapid border intervention requested by Greece," said Leggeri.

Greek authorities will be coordinating the 1,500 officers deployed by Frontex. The EU has also granted $780 million in assistance to Greece to prevent migrants from flowing into the bloc through its borders.