The men, all from London and aged in their 20s, were held on suspicion of explosive offences and preparation of a terrorist act. The five men arrested Sunday in connection with an attempted terror attack at a military base in southwest England are British nationals, authorities said Monday. Key points and original sources are listed below.

• The men, all from London and aged in their 20s, were held on suspicion of explosive offences and preparation of a terrorist act.S1

• The five men arrested Sunday in connection with an attempted terror attack at a military base in southwest England are British nationals, authorities said Monday.S2

• The counter-terrorism police have issued an updateS3