inAppBrowser Cordova plugin default for all links not working

I'm trying to set all links opened within my app to use the "_system". I've set this in my onDeviceReady(), and it still doesn't work. Instead every link opens through the cordova browser. Could someone please tell me what I'm doing wrong?

function onDeviceReady() {
window.open = cordova.InAppBrowser.open('_system');
}