US already delivered 11 MK 15 Phalanx Block 1B CIWS guns to Taiwan.

According to information published by LTN on April 2, 2023, 11 MK 15 Phalanx Block 1B CIWS guns have been delivered to Taiwan, and another 2 sets will arrive by the end of this year.
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A MK 15 Phalanx close-in weapons system is test-fired on the flight deck aboard the aircraft carrier USS Carl Vinson. (Picture source: US Navy)

The MK 15 Phalanx Close-In Weapon System (CIWS) is a fast-reaction, radar-guided, 20-millimeter gun weapon system designed to provide U.S. Navy ships with an inner layer point defense capability against anti-ship missiles, aircraft, and littoral warfare threats that have penetrated other fleet defenses.

The system is capable of autonomously detecting, evaluating, tracking, engaging, and performing kill assessments against threats. The current variant, Block 1B, also counters asymmetric warfare threats by integrating a stabilized, Electro-Optic sensor to engage small high-speed surface craft, aircraft, helicopters, and unmanned aerial systems.

The Phalanx CIWS has been in continuous production, upgrade, and overhaul since 1978. Its Block 0 configuration was first installed in 1980 on the USS Coral Sea, followed by the Block 1 configuration on the USS Wisconsin in 1988, and the Block 1B configuration on the USS Underwood in 1999.

Weighing 13,600 pounds (6,120 kg) in its Block 1B configuration, the CIWS is designed to deliver impressive firepower for multiple threat scenarios. When facing anti-ship missiles and aircraft, the system boasts a firing rate of 4,500 rounds per minute.

In situations involving asymmetric threats, the CIWS can still deliver an impressive 3,000 rounds per minute. With a magazine capacity of 1,550 rounds, the system can sustain its defensive capabilities for an extended period.