they are establishing military base for sure, during peace time these base can be used for nav,rescue & shelter etc, but during war time it will be used as military base, supports etc.
that been said any rising power will expand its influence, from Spanish to brit to japan to US, there are tons of similar cases. in the 80s china don't really care about secure sea lane etc since it doesn't export much, but now most china import/export go through SCS and west pacific, and it import most its oil and commodities via these region. it become clear for them, security and influence in the region is much more important then before. the one belt one road plan through central asia is a way for china to by pass its reliance on sea route.
I don't think china even care about the resource in SCS, they have $$$, which they can buy resource from Russia/middle east/Canada/ausse/Africa/S.america. of course resource in SCS is just a bonus compare to secure sea lane. most these trade go through SCS or other sea lane
that been said any rising power will expand its influence, from Spanish to brit to japan to US, there are tons of similar cases. in the 80s china don't really care about secure sea lane etc since it doesn't export much, but now most china import/export go through SCS and west pacific, and it import most its oil and commodities via these region. it become clear for them, security and influence in the region is much more important then before. the one belt one road plan through central asia is a way for china to by pass its reliance on sea route.
I don't think china even care about the resource in SCS, they have $$$, which they can buy resource from Russia/middle east/Canada/ausse/Africa/S.america. of course resource in SCS is just a bonus compare to secure sea lane. most these trade go through SCS or other sea lane