Whenever the President or any agency of the United States Government is authorized or required by or pursuant to the laws of the United States to render or provide to or to receive or accept from Taiwan, any performance, communication, assurance, undertaking, or other action, such action shall, in the manner and to the extent directed by the President, be rendered or provided to, or received or accepted from, an instrumentality established by Taiwan which the President determines has the necessary authority under the laws applied by the people on Taiwan to provide assurances and take other actions on behalf of Taiwan in accordance with this Act.

【语法分析】

1. 时间从句：Whenever the President or any agency of the United States Government is authorized or required by or pursuant to the laws of the United States to render or provide to or to receive or accept from Taiwan, any performance, communication, assurance, undertaking, or other action

2. 主句：such action shall, in the manner and to the extent directed by the President, be rendered or provided to, or received or accepted from, an instrumentality established by Taiwan which the President determines has the necessary authority under the laws applied by the people on Taiwan to provide assurances and take other actions on behalf of Taiwan in accordance with this Act.

3. 先回答你的问题：has 的主语是which，which 指代 instrumentality（机构）

4. 在主句中：

（1）主句：such action shall, in the manner and to the extent directed by the President, be rendered or provided to, or received or accepted from, an instrumentality established by Taiwan

（2）定语从句：which the President determines has the necessary authority under the laws applied by the people on Taiwan to provide assurances and take other actions on behalf of Taiwan in accordance with this Act，修饰instrumentality。

5. 在定语从句中：

（1）which作主语，

（2）the President determines 作定语修饰which，

（3）has作谓语，

（4）the necessary authority 作宾语

（5）under the laws applied by the people on Taiwan （方式状语）

（6）to provide assurances and take other actions on behalf of Taiwan in accordance with this Act作定语，修饰authority。

【主句划分】such action （主语）shall, in the manner and to the extent directed by the President, be rendered or provided to, or received or accepted from（谓语）,an instrumentality established by Taiwan （宾语）

【定语从句划分】which （主语）the President determines （定语） has （谓语） the necessary authority （宾语）under the laws applied by the people on Taiwan （方式状语）to provide assurances and take other actions on behalf of Taiwan in accordance with this Act. （定语修饰the necessary authority）