A government can do only what is feasible given the political and economic context.

Police can only act on intelligence.

The police force cannot be completely independent of the executive government.

The voter does not vote only on one issue, the voter votes on a multiplicity of issues.

No matter what political reasons are given for war, the underlying reason is always economic.

Two successive commissioners in London police were fired by the mayor that came into office. That doesn't mean the police in London is not independent and does not exercise powers. Ultimately it is the political executive that has to answer.