In the six months prior to the onset of war, there had been an escalation of Irish Republican Army violence and a bombing campaign in Britain under the new leadership of Seán Russell. De Valera, who had tolerated the IRA as recently as 1936, responded with the Offences against the State Act, 1939. Upon the outbreak of the main conflict in September, subversive activity was regarded as endangering the security of the state. There were fears that the United Kingdom, eager to secure Irish ports for their air and naval forces, might use the attacks as a pretext for an invasion of Ireland and a forcible seizure of the assets in question. Furthermore, the possibility that the IRA (in line with the Irish republican tradition of courting allies in Europe) might link up with German agents, thereby compromising Irish non-involvement, was considered.