[Using xsltproc]: output of running XSLT is missing xmlns attributes

Question

I have an XML file:

<?xml version="1.0" encoding="UTF-8"?>
  <exp:Export Version="3.0"
xmlns:L7p="http://www.layer7tech.com/ws/policy"
xmlns:exp="http://www.layer7tech.com/ws/policy/export" xmlns:wsp="http://schemas.xmlsoap.org/ws/2002/12/policy">
<exp:References/>
<wsp:Policy xmlns:L7p="http://www.layer7tech.com/ws/policy" xmlns:wsp="http://schemas.xmlsoap.org/ws/2002/12/policy">
    <wsp:All wsp:Usage="Required">
        <L7p:AuditAssertion>
            <L7p:Level stringValue="INFO"/>
        </L7p:AuditAssertion>
        <L7p:AuditDetailAssertion>
            <L7p:Detail stringValue="2222"/>
        </L7p:AuditDetailAssertion>
        <L7p:AuditDetailAssertion>
            <L7p:Detail stringValue="333"/>
            <L7p:Level stringValue="WARNING"/>
        </L7p:AuditDetailAssertion>
        <wsp:OneOrMore wsp:Usage="Required">
            <wsp:OneOrMore wsp:Usage="Required">
                <L7p:AuditDetailAssertion>
                    <L7p:Detail stringValue="444"/>
                    <L7p:Level stringValue="FINE"/>
                </L7p:AuditDetailAssertion>
            </wsp:OneOrMore>
            <wsp:OneOrMore wsp:Usage="Required">
                <L7p:AuditDetailAssertion>
                    <L7p:Detail stringValue="555"/>
                    <L7p:Level stringValue="FINEST"/>
                </L7p:AuditDetailAssertion>
            </wsp:OneOrMore>
        </wsp:OneOrMore>
    </wsp:All>
</wsp:Policy>
</exp:Export>`

and I want to remove all of the

L7p:AuditDetailAssertion/L7p:Level 

elements.

I am using the xsltproc from Redhat 7 to run the XSLT.

Here's the XSLT that I am using:

<?xml version="1.0"?>
<xsl:stylesheet
xmlns:L7p="http://www.layer7tech.com/ws/policy"
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  version="1.0">

  <xsl:output omit-xml-declaration="no" indent="yes"/>
  <xsl:strip-space elements="*"/>

  <!-- TEMPLATE #1 -->
  <xsl:template match="node()|@*">
    <xsl:copy>
      <xsl:apply-templates select="node()|@*"/>
    </xsl:copy>
  </xsl:template>

  <!-- TEMPLATE #2 -->
  <xsl:template match="L7p:AuditDetailAssertion/L7p:Level" />

</xsl:stylesheet>

and the output that I am getting is:

<?xml version="1.0"?>
<exp:Export xmlns:L7p="http://www.layer7tech.com/ws/policy"   xmlns:exp="http://www.layer7tech.com/ws/policy/export" xmlns:wsp="http://schemas.xmlsoap.org/ws/2002/12/policy" Version="3.0">
  <exp:References/>
  <wsp:Policy>
    <wsp:All wsp:Usage="Required">
      <L7p:AuditAssertion>
        <L7p:Level stringValue="INFO"/>
      </L7p:AuditAssertion>
      <L7p:AuditDetailAssertion>
        <L7p:Detail stringValue="2222"/>
      </L7p:AuditDetailAssertion>
      <L7p:AuditDetailAssertion>
        <L7p:Detail stringValue="333"/>
      </L7p:AuditDetailAssertion>
      <wsp:OneOrMore wsp:Usage="Required">
        <wsp:OneOrMore wsp:Usage="Required">
          <L7p:AuditDetailAssertion>
            <L7p:Detail stringValue="444"/>
          </L7p:AuditDetailAssertion>
        </wsp:OneOrMore>
        <wsp:OneOrMore wsp:Usage="Required">
          <L7p:AuditDetailAssertion>
            <L7p:Detail stringValue="555"/>
          </L7p:AuditDetailAssertion>
        </wsp:OneOrMore>
      </wsp:OneOrMore>
    </wsp:All>
  </wsp:Policy>
</exp:Export>

Notice that in the output, the wsp:Policy is missing the two "xmlns" attributes, "xmlns:L7p" and "xmlns:wsp".

How can I get the XSLT to include those "xmlns" attributes on the wsp:Policy element in the output XML?