Can you nest the <menu> tag? semantic HTML

Question

Is it okay to nest the <menu> tag? eg:

<menu>
  <li>1</li>
  <li>2
    <menu>
        <li>2.1</li>
        <li>2.1</li>
    </menu>
  </li>
  <li>3</li>
</menu>

or shoud I use <ul> inside? eg:

<menu>
  <li>1</li>
  <li>2
    <ul>
        <li>2.1</li>
        <li>2.1</li>
    </ul>
  </li>
  <li>3</li>
</menu>

Have a good day and thank you!