Jetty running on 1.6 JVM cannot run webapp compiled on Java 1.6

I am trying to run a very simple Java webapp on a Jetty web server (v9.0).

Using maven, I built and created war, and as you can see in the manifest file, I used Java 1.6u43 to compile on OS X

Contents META-INF / MANIFEST.MF

Manifest-Version: 1.0
Archiver-Version: Plexus Archiver
Created-By: Apache Maven
Built-By: irraju
Build-Jdk: 1.6.0_43

I am running Jetty on Ubuntu, and as you can see, I have a slightly higher version of java 1.6.0_45. If java is backward compatible, my java application should work on the marina, but it does not work with an unsupported minor version

root# java -version
java version "1.6.0_45"
Java(TM) SE Runtime Environment (build 1.6.0_45-b06)
Java HotSpot(TM) Client VM (build 20.45-b01, mixed mode, sharing)

root# java -DDEBUG -jar start.jar 
Exception in thread "main" java.lang.UnsupportedClassVersionError: org/eclipse/jetty/start/Main : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: org.eclipse.jetty.start.Main. Program will exit.

, Java 1,7 JVM 1.6 *. , , ENV 1,6 *, ENV JVM.

Tomcat, java 1.6.0_45, . - ?