Mutual Defense Treaty 1951 Mutual Defense Treaty 1951 Mutual Defense Treaty 1951 Mutual Defense Treaty 1951 Mutual Defense Treaty Article IV Article IV 1951 Mutual Defense Treaty 1951 U.S–Philippines Mutual Defense Treaty (MDF) US-Philippines Mutual Defense Treaty US-Philippines Mutual Defense Treaty 1951 mutual defense treaty Mutual Defense Pact of 1951 1951 U.S.-Philippine Mutual Defense Treaty Mutual Defense Treaty U.S.–Philippines Mutual Defense Treaty 1951 Mutual Defense Treaty