ISTANBUL — Turkey’s Parliament approved plans on Thursday to send troops to Libya, escalating what has become a chaotic proxy war between multiple powers for control of the oil-rich country.

The Turkish deployment, a dramatic intervention championed by President Recep Tayyip Erdogan, aims to bolster the fragile United Nations-backed government in Tripoli after nine months of siege from rebel forces based in eastern Libya.

The size and nature of the military deployment was unclear. But coming just months after Turkey’s third military incursion into Syria, it expands Turkey’s military footprint in a volatile region and, analysts say, offers new evidence of its growing self-confidence as a regional power.

For Libya’s embattled government, Mr. Erdogan has become an essential patron. Already this year, he has sent military advisers, arms and a fleet of 20 drones to defend Tripoli from the forces of Gen. Khalifa Hifter, which control much of eastern Libya and are backed by Russia, Saudi Arabia, the United Arab Emirates and Egypt.