He is at heart a populist and the Republican parties unpopular ideas (less free things, more war) are being forced upon him, he doesnt really support them.
Its popular stuff however, he supports (less taxes, anti illegal immigration, less regulations)
He isnt a true Republican and definitely not a true conservative, for the good or the bad.
Mostly, Trump wants a win. He wants to withdraw from Syria and Afghanistan even though we didnt win (it want really something we could win in) because the people are tired of it.
He defeated ISIS with extra defense spending.
He is willing to go to war, for his Saudi friends. He vetoed the Yemen withdrawl